Trimix_(breathing_gas)

# Trimix (breathing gas) ## Microsim ### Live player <div class="microsim-player"> <iframe src="https://editor.p5js.org/sciencenibber/full/4VEY1wJew" width="100%" height="620" frameborder="0" sandbox="allow-scripts allow-same-origin"></iframe> </div> <div class="microsim-fallback"> <img src="Microsims/thumbs/Trimix_(breathing_gas).png" alt="Trimix_(breathing_gas) microsim poster" style="width:100%;border:1px solid #4445;border-radius:6px;"> <p><em>Live microsim (desktop) · <a href="https://editor.p5js.org/sciencenibber/sketches/4VEY1wJew">open sketch in the p5.js editor</a></em></p> </div> **Editor URL:** https://editor.p5js.org/sciencenibber/sketches/4VEY1wJew **Description (100 words):** Two panes share one rig. On the left, a chamber of bouncing colored particles tracks the mix — orange dots are O2, blue are He, grey are N2 — and the frame tints green, amber, or red as ppO2 crosses the 1.4 bar working limit and 1.6 bar deco ceiling. On the right, a yellow diver descends a 0–120 m water column with surface bubbles trailing up. Three sliders compose the gas (%O2, %He) and choose the depth; live readouts spell out the three partial pressures, the Maximum Operating Depth, and the Equivalent Narcotic Depth. ```js // ===================================================================== // Trimix_(breathing_gas).js -- Wikitube microsim // Article: Trimix (breathing gas) en.wikitube.io/wiki/Trimix_(breathing_gas) // Room: Helium Pattern: E (particle system, kinetic phenomena) // --------------------------------------------------------------------- // Idea: a live two-pane diving rig. // // LEFT PANE -- "gas chamber" of bouncing colored particles whose // populations track the breathing-mix fractions. // O2 = warm/hot tone (red-orange) // He = cool tone (blue) // N2 = neutral STRUCT grey // Particles speed up with ambient pressure (more // collisions per second, faster-looking gas) so the // reader can see the qualitative jump in gas density // between a 30 m and a 90 m dive. // // RIGHT PANE -- a vertical depth column from the surface to 120 m, // with a diver glyph that descends with the depth // slider. Tick marks every 10 m. The chamber pane // border + tint encode the ppO2 safety band, and the // bottom-row readouts spell out partial pressures, // MOD, and END so the reader can read the mix as a // physical state, not just three percentages. // // BOTTOM -- three sliders: %O2 (10-21), %He (0-70), depth (0-120 m). // ppO2 thresholds: 1.4 bar working, 1.6 bar deco max. // Above 1.6 bar the chamber turns red (toxic); // between 1.4 and 1.6 it turns amber (deco only). // // Canonical relations (visible on the bottom HUD and in code): // P_amb(D) = 1 + D/10 (bar, fresh-water hydrostatic) // pp_i = f_i * P_amb (Dalton's law of partial pressures) // MOD = 10 * (ppO2_max / fO2 - 1) (m, with ppO2_max = 1.4 bar) // END = (1 - fHe) * (D + 10) - 10 (m, He-only-non-narcotic form) // // History notes (for the Obsidian article body, not the canvas): // First applied by U.S. Navy diver Max Nohl in 1937. Refined for // commercial saturation diving in the 1960s. Standard for tech // dives below ~50 m today. // // Conventions (Wikitube Betterfire Standard v0): // * single ARTICLE constant at the top, single quotes // * p5.disableFriendlyErrors = true to keep the editor console clean // * all non-ASCII (Greek, dots, arrows) lives in COMMENTS ONLY; // every text() string literal is pure ASCII // * Energy-room palette (P5_JS_EDITOR section 4) // * every createSlider carries an explicit .position(x, y).size(w) // ===================================================================== const ARTICLE = 'Trimix_(breathing_gas)'; const TITLE = ARTICLE.replace(/_/g, ' '); p5.disableFriendlyErrors = true; // ----- Energy room palette (P5_JS_EDITOR section 4) ------------------ const BG = 18; const FG = 240; const DIM = [240, 240, 240, 140]; const HOT = [220, 110, 60]; // oxygen (red-orange, warm) const COLD = [60, 130, 220]; // helium (blue, cool) const STRUCT = [120, 130, 150]; // nitrogen / structural grey const TRAJ = [240, 220, 80]; // accent / diver glyph const SAFE = [120, 220, 140]; // ppO2 safe-band tint (green) const CAUTION = [240, 180, 80]; // ppO2 deco-only tint (amber) const DANGER = [240, 90, 90]; // ppO2 toxic tint (red) const SCRATCH = [120, 120, 120, 90]; // grid lines // ----- Mix bounds + safety thresholds -------------------------------- const FO2_MIN = 10; // % (deep mixes go as low as 10% O2) const FO2_MAX = 21; // % (atmospheric air ceiling for our slider) const FHE_MIN = 0; // % const FHE_MAX = 70; // % (10/70 is a deep cave / wreck staple) const DEPTH_MAX = 120; // m const PPO2_WORK = 1.4; // bar, working oxygen partial-pressure limit const PPO2_DECO = 1.6; // bar, decompression-only ceiling // ----- Layout: two panes + control row ------------------------------- const PANE_W = 330; const LEFT_X = 14; const LEFT_Y = 70; const LEFT_H = 320; const RIGHT_X = LEFT_X + PANE_W + 16; const RIGHT_Y = LEFT_Y; const RIGHT_H = LEFT_H; // ----- Particle field (Pattern E core) ------------------------------- const N_PARTICLES = 220; let particles = []; // each is {x, y, vx, vy, kind: 'O2'|'He'|'N2'} // ----- Controls (each gets .position(...).size(...) -- never floating) --- let fo2Slider, fheSlider, depthSlider; function setup() { createCanvas(720, 520); pixelDensity(2); textFont('system-ui'); // Sliders docked in a clean control row below the panes. fo2Slider = createSlider(FO2_MIN, FO2_MAX, 18, 1).position( 18, 440).size(170); fheSlider = createSlider(FHE_MIN, FHE_MAX, 45, 1).position( 18, 470).size(170); depthSlider = createSlider(0, DEPTH_MAX, 60, 1).position(360, 470).size(310); reseedParticles(); } // Initialize the particle field once at startup with random positions // and unit-magnitude velocities. Species assignment is rewritten every // frame in assignKinds() so the population tracks the sliders. function reseedParticles() { particles.length = 0; for (let i = 0; i < N_PARTICLES; i++) { particles.push({ x: random(LEFT_X + 8, LEFT_X + PANE_W - 8), y: random(LEFT_Y + 8, LEFT_Y + LEFT_H - 8), vx: random(-1, 1), vy: random(-1, 1), kind: 'N2' }); } } // Stable kind assignment by index: keeps the chamber looking // continuous as the sliders move. Particles 0..nO2-1 are oxygen, // the next nHe are helium, the rest are nitrogen. function assignKinds(fO2, fHe) { const nO2 = round(N_PARTICLES * fO2); const nHe = round(N_PARTICLES * fHe); for (let i = 0; i < particles.length; i++) { if (i < nO2) particles[i].kind = 'O2'; else if (i < nO2 + nHe) particles[i].kind = 'He'; else particles[i].kind = 'N2'; } } function draw() { background(BG); // --- Read controls once at the top of the frame ------------------ const fO2pct = fo2Slider.value(); let fHepct = fheSlider.value(); // Cap fHe so fO2 + fHe <= 100 (no negative-N2 mixes) fHepct = min(fHepct, max(0, 100 - fO2pct)); const fO2 = fO2pct / 100; const fHe = fHepct / 100; const fN2 = max(0, 1 - fO2 - fHe); const D = depthSlider.value(); // m const P_amb = 1 + D / 10; // bar const ppO2 = fO2 * P_amb; const ppHe = fHe * P_amb; const ppN2 = fN2 * P_amb; // MOD: working limit at ppO2 = 1.4 bar. Negative MOD => already // toxic at the surface (handled at readout time as 'surface only'). const MOD = 10 * (PPO2_WORK / fO2 - 1); // END: He-only-non-narcotic form. Equivalent depth on air with the // same partial pressure of narcotic gas (N2 + O2). const END = (1 - fHe) * (D + 10) - 10; // Status band derived from ppO2. let statusCol; if (ppO2 > PPO2_DECO) statusCol = DANGER; else if (ppO2 > PPO2_WORK) statusCol = CAUTION; else statusCol = SAFE; assignKinds(fO2, fHe); // --- Order: chamber field -> particles -> column -> readouts -> HUD. // Later layers always paint on top. drawChamber(statusCol); stepAndDrawParticles(P_amb); drawDepthColumn(D, P_amb); drawReadouts(fO2, fHe, fN2, D, P_amb, ppO2, ppHe, ppN2, MOD, END, statusCol); drawControlLabels(fO2pct, fHepct, D); drawHUD(); } // ===================================================================== // LEFT PANE -- gas chamber (Pattern E core) // ===================================================================== function drawChamber(statusCol) { // Background tinted by ppO2 status (safe/caution/danger). noStroke(); fill(statusCol[0], statusCol[1], statusCol[2], 18); rect(LEFT_X, LEFT_Y, PANE_W, LEFT_H); // Border colored by status -- the reader sees red-edged frame at a // glance when ppO2 has gone toxic. noFill(); stroke(statusCol[0], statusCol[1], statusCol[2], 200); strokeWeight(1.5); rect(LEFT_X, LEFT_Y, PANE_W, LEFT_H); // Pane label. noStroke(); fill(...DIM); textAlign(LEFT, BOTTOM); textSize(11); text('gas chamber (Dalton mix)', LEFT_X + 6, LEFT_Y - 4); } // Step every particle one tick, reflect off walls, then draw colored. // Speed scales with sqrt(P_amb) so denser ambient reads as livelier gas. function stepAndDrawParticles(P_amb) { const vScale = constrain(sqrt(P_amb) * 0.9, 0.6, 4.0); const xMin = LEFT_X + 4, xMax = LEFT_X + PANE_W - 4; const yMin = LEFT_Y + 4, yMax = LEFT_Y + LEFT_H - 4; noStroke(); for (let i = 0; i < particles.length; i++) { const pt = particles[i]; pt.x += pt.vx * vScale; pt.y += pt.vy * vScale; if (pt.x < xMin) { pt.x = xMin; pt.vx = -pt.vx; } if (pt.x > xMax) { pt.x = xMax; pt.vx = -pt.vx; } if (pt.y < yMin) { pt.y = yMin; pt.vy = -pt.vy; } if (pt.y > yMax) { pt.y = yMax; pt.vy = -pt.vy; } let col, rad; if (pt.kind === 'O2') { col = HOT; rad = 3.4; } else if (pt.kind === 'He') { col = COLD; rad = 2.2; } else { col = STRUCT; rad = 3.0; } fill(col[0], col[1], col[2], 220); ellipse(pt.x, pt.y, rad * 2, rad * 2); } // Legend (top-right of the chamber pane). const lx = LEFT_X + PANE_W - 96; const ly = LEFT_Y + 8; textAlign(LEFT, TOP); textSize(10); fill(HOT[0], HOT[1], HOT[2]); ellipse(lx, ly + 5, 6, 6); fill(...DIM); text('O2', lx + 10, ly); fill(COLD[0], COLD[1], COLD[2]); ellipse(lx, ly + 21, 6, 6); fill(...DIM); text('He', lx + 10, ly + 16); fill(STRUCT[0], STRUCT[1], STRUCT[2]); ellipse(lx, ly + 37, 6, 6); fill(...DIM); text('N2', lx + 10, ly + 32); } // ===================================================================== // RIGHT PANE -- vertical depth column with descending diver // ===================================================================== function drawDepthColumn(D, P_amb) { // Frame noFill(); stroke(...SCRATCH); strokeWeight(1); rect(RIGHT_X, RIGHT_Y, PANE_W, RIGHT_H); // Water gradient: light surface to dark abyss in 24 strips. noStroke(); const stripeH = RIGHT_H / 24; for (let i = 0; i < 24; i++) { const t = i / 23; const r = lerp(40, 8, t); const g = lerp(80, 18, t); const b = lerp(150, 40, t); fill(r, g, b, 160); rect(RIGHT_X + 1, RIGHT_Y + 1 + i * stripeH, PANE_W - 2, stripeH + 1); } // Surface line + label stroke(...TRAJ); strokeWeight(1.5); line(RIGHT_X, RIGHT_Y + 1, RIGHT_X + PANE_W, RIGHT_Y + 1); noStroke(); fill(...DIM); textAlign(LEFT, TOP); textSize(10); text('surface (1 bar)', RIGHT_X + 6, RIGHT_Y + 4); // Depth tick marks every 10 m. textAlign(LEFT, CENTER); for (let m = 10; m <= DEPTH_MAX; m += 10) { const py = map(m, 0, DEPTH_MAX, RIGHT_Y + 4, RIGHT_Y + RIGHT_H - 6); stroke(...SCRATCH); strokeWeight(1); line(RIGHT_X + 4, py, RIGHT_X + 18, py); noStroke(); fill(...DIM); textSize(9); text(m + ' m', RIGHT_X + 22, py); } // Diver glyph at the current depth. const dy = map(D, 0, DEPTH_MAX, RIGHT_Y + 4, RIGHT_Y + RIGHT_H - 6); const dx = RIGHT_X + PANE_W / 2 + 30; // Bubble trail rising above the diver. fill(255, 255, 255, 90); noStroke(); for (let i = 0; i < 5; i++) { const by = dy - 10 - ((frameCount * 0.6 + i * 13) % 60); if (by > RIGHT_Y + 4) { const br = 2 + i * 0.4; ellipse(dx + 6, by, br * 2, br * 2); } } // Body (yellow accent against the dark water). fill(...TRAJ); ellipse(dx, dy, 10, 14); // torso ellipse(dx, dy - 10, 7, 7); // head stroke(...TRAJ); strokeWeight(2); line(dx - 4, dy + 8, dx - 9, dy + 14); line(dx + 4, dy + 8, dx + 9, dy + 14); noStroke(); // Ambient-pressure tag next to the diver. fill(...DIM); textAlign(LEFT, CENTER); textSize(10); text('P_amb = ' + nf(P_amb, 0, 2) + ' bar', dx + 16, dy); // Pane label. noStroke(); fill(...DIM); textAlign(LEFT, BOTTOM); textSize(11); text('depth column (0 - 120 m)', RIGHT_X + 6, RIGHT_Y - 4); } // ===================================================================== // READOUTS -- status pill + partial pressures + MOD/END // ===================================================================== function drawReadouts(fO2, fHe, fN2, D, P_amb, ppO2, ppHe, ppN2, MOD, END, statusCol) { // --- Status pill under the chamber --- const sx = LEFT_X; const sy = LEFT_Y + LEFT_H + 8; const sw = PANE_W; const sh = 20; noStroke(); fill(statusCol[0], statusCol[1], statusCol[2], 50); rect(sx, sy, sw, sh, 3); fill(statusCol[0], statusCol[1], statusCol[2]); textAlign(LEFT, CENTER); textSize(11); let statusText; if (statusCol === DANGER) statusText = 'ppO2 > 1.6 bar TOXIC'; else if (statusCol === CAUTION) statusText = 'ppO2 > 1.4 bar DECO ONLY'; else statusText = 'ppO2 within working limit'; text(statusText, sx + 8, sy + sh / 2); // --- Partial pressures under the depth column --- const px = RIGHT_X; const py = LEFT_Y + LEFT_H + 8; fill(...DIM); textAlign(LEFT, CENTER); textSize(11); text('ppO2 = ' + nf(ppO2, 0, 2) + ' bar', px, py + 4); text('ppN2 = ' + nf(ppN2, 0, 2) + ' bar', px + 110, py + 4); text('ppHe = ' + nf(ppHe, 0, 2) + ' bar', px + 220, py + 4); // MOD / END just below. fill(FG); textSize(12); const modLabel = (MOD >= 0) ? (nf(MOD, 0, 1) + ' m') : 'surface only'; const endLabel = (END >= 0) ? (nf(END, 0, 1) + ' m') : '< 0 m'; text('MOD = ' + modLabel, px, py + 24); text('END = ' + endLabel, px + 165, py + 24); } // Slider value labels beside each slider so the reader can see the // current numeric setting without hovering the browser-native handle. function drawControlLabels(fO2pct, fHepct, D) { noStroke(); fill(...DIM); textAlign(LEFT, CENTER); textSize(11); text('% O2 ' + fO2pct, 198, 450); text('% He ' + fHepct, 198, 480); text('depth ' + D + ' m', 680, 480); } // ===================================================================== // HUD -- title, URL, control hints, canonical equation // ===================================================================== function drawHUD() { // Top-left: title + Wikitube URL (Betterfire Standard rule 2) noStroke(); fill(FG); textAlign(LEFT, TOP); textSize(20); text(TITLE, 14, 12); fill(...DIM); textSize(12); text('Wikitube microsim . en.wikitube.io/wiki/Trimix_(breathing_gas)', 14, 36); // Top-right: control hints (Betterfire Standard rule 3) textAlign(RIGHT, TOP); textSize(10); text('slide %O2 and %He to compose the mix', width - 14, 12); text('slide depth to descend the diver', width - 14, 24); text('chamber tints with ppO2 safety band', width - 14, 36); // Bottom-right: canonical equation (Betterfire Standard rule 4) textAlign(RIGHT, BOTTOM); fill(FG); textSize(12); text('MOD = 10 * (1.4 / fO2 - 1) END = (1 - fHe) * (D + 10) - 10', width - 14, height - 6); } // ===================================================================== // End of Trimix_(breathing_gas).js -- Wikitube microsim, Helium room, Pattern E. // ===================================================================== ``` ## Links (Wikipedia order)  `14th_CMAS_Underwater_Photography_World_Championship` · `1973_Mount_Gambier_cave_diving_accident` · `1992_cageless_shark-diving_expedition` · `2026_Dhekunu_Kandu_cave_diving_incident` · `8A4-class_ROUV` · `AAI_underwater_revolver` · `ABISMO` · `ADS_amphibious_rifle` · `AIDA_Hellas` · `AIDA_International` · `AN/BLQ-11_Long-Term_Mine_Reconnaissance_System` · `APS_underwater_rifle` · `AP_Diving` · `ASM-DT_amphibious_rifle` · `Activated_carbon` · `Adrian_Biddle` · `Advanced_Open_Water_Diver` · `Advanced_SEAL_Delivery_System` · `Aerosinusitis` · `Aerospace_Medical_Association` · `Agnes_Milowka` · `Air_embolism` · `Air_line` · `Airlift_(dredging_device)` · `Akihiko_Hoshide` · `Albert_A._Bühlmann` · `Albert_Falco` · `Albert_R._Behnke` · `Albert_Tillman` · `Alessia_Zecchini` · `Alexey_Molchanov` · `Alf_O._Brubakk` · `Allan_Bridge` · `Alpazat_cave_rescue` · `Alternative_air_source` · `Alternobaric_vertigo` · `Altitude_diving` · `Aluminaut` · `Ama_(diving)` · `Amelia_Behrens-Furniss` · `American_Academy_of_Underwater_Sciences` · `American_Canadian_Underwater_Certifications` · `American_Nitrox_Divers_International` · `American_submarine_NR-1` · `Anders_Franzén` · `Andreas_Mogensen` · `Andreas_Rechnitzer` · `Andrew_Abercromby` · `Andrew_J._Feustel` · `Andrew_Wight` · `Andy_Torbet` · `Anna_Marguerite_McCann` · `Annelie_Pompe` · `Anti-fog` · `Anxiety` · `Apeks` · `Aqua-Lung` · `Aqua_Lung/La_Spirotechnique` · `Aqua_Lung_America` · `Aquanaut` · `Aquarius_Reef_Base` · `Aquathlon_(underwater_wrestling)` · `Archaeology_of_shipwrecks` · `Archimède` · [[Argon]] · `Argox` · `Aristotelis_Zervoudis` · `Army_engineer_diver` · `Arne_Zetterström` · `Arthur_C._Clarke` · `Arthur_J._Bachrach` · `Artificial_Reef_Society_of_British_Columbia` · `Artur_Kozłowski_(speleologist)` · `Ascending_and_descending_(diving)` · `Asphyxia` · `Association_nationale_des_moniteurs_de_plongée` · `Association_of_Diving_Contractors_International` · `Atlantis_ROV_Team` · `Atmospheric_diving_suit` · `Atrial_septal_defect` · `Audrey_Mestre` · `Auguste_Denayrouze` · `Auguste_Piccard` · `Augustus_Siebe` · `Australian_Diver_Accreditation_Scheme` · `Australian_Underwater_Federation` · `Autonomous_diver` · `Avascular_necrosis` · `Avelo_diving_system` · `Bailout_bottle` · `Barodontalgia` · `Barotrauma` · `Basic_Cave_Diving:_A_Blueprint_for_Survival` · `Bathyscaphe` · `Bathysphere` · `Ben_Cropp` · `Bernard_Delemotte` · `Berry_L._Cannon` · `Beuchat` · `Bill_Nagle` · `Bill_Todd` · `Billy_Deans_(diver)` · `Bob_Behnken` · `Bob_Halstead` · `Bolt_snap` · `Booster_pump` · [[Breathing_gas]] · `Breathing_performance_of_regulators` · `Bret_Gilliam` · `Brian_Andrew_Hills` · `Brian_Kakuk` · `Brian_Skerry` · `British_Freediving_Association` · `British_Octopush_Association` · `British_Sub-Aqua_Club` · `British_Underwater_Sports_Association` · `Buddy_breathing` · `Buddy_check` · `Buddy_diving` · `Built-in_breathing_system` · `Buoyancy_compensator_(diving)` · `Byford_Dolphin` · `Bühlmann_decompression_algorithm` · `CMAS**_scuba_diver` · `CMAS*_scuba_diver` · `CMAS_Europe` · `COTSBot` · `CUMA` · `CURV` · `Canadian_Armed_Forces_Divers` · `Candice_Farmer` · `Canoe_and_kayak_diving` · `Carbon_dioxide_scrubber` · `Carbon_monoxide_poisoning` · `Carlos_Coste` · `Cascade_filling_system` · `Catherine_Coleman` · `Cathy_Church` · `Cave_Divers_Association_of_Australia` · `Cave_Diving_Group` · `Cave_diving` · `Charles_Anthony_Deane` · `Charles_Momsen` · `Charles_Spalding` · `Charles_T._Meide` · `Charles_Wesley_Shilling` · `Checklist` · `Children_in_scuba_diving` · `Chris_Hadfield` · `Christian_J._Lambertsen` · `Christopher_E._Gerty` · `Cis-Lunar` · `Civil_liability_in_recreational_diving` · `Claudia_Serpieri` · `Clayton_Anderson` · `Cleaning_and_disinfection_of_personal_diving_equipment` · `Clearance_Divers_Life_Support_Equipment` · `Clearance_Diving_Branch_(RAN)` · `Clearance_diver` · `Clive_Cussler` · `Cláudio_Coutinho` · `Code_of_practice` · `Cold_shock_response` · `Comando_Raggruppamento_Subacquei_e_Incursori_Teseo_Tesei` · `Combat_sidestroke` · `Comhairle_Fo-Thuinn` · `Commercial_diver_registration_in_South_Africa` · `Commercial_diving` · `Commercial_offshore_diving` · `Compagnie_maritime_d'expertises` · `Competency-based_learning` · `Compression_arthralgia` · `Confédération_Mondiale_des_Activités_Subaquatiques` · `Constant_weight_bi-fins` · `Constant_weight_without_fins` · `Continental_Shelf_Station_Two` · `Contingency_plan` · `Convention_on_the_Protection_of_the_Underwater_Cultural_Heritage` · `Coral_Reef_Alliance` · `Cosmos_CE2F_series` · `Cotton_Coulson` · `Craig_B._Cooper` · `Craig_Challen` · `Craig_McKinley_(physician)` · `Cressi-Sub` · `Cristina_Zenato` · `DESCO` · `DIN_7876` · `DSRV-1_Mystic` · `DSRV-2_Avalon` · `DSV-5_Nemo` · `DSV_Alvin` · `DSV_Limiting_Factor` · `DSV_Sea_Cliff` · `DSV_Shinkai` · `DSV_Shinkai_2000` · `DSV_Shinkai_6500` · `DSV_Turtle` · `Dacor_(scuba_diving)` · `Dafydd_Williams` · `Dalton's_law` · `Danai_Varveri` · `Daniel_M._Tani` · `Dave_Mullins_(freediver)` · `Dave_Shaw` · `David_Attenborough` · `David_Bright_(diver)` · `David_Doubilet` · `David_Gibbins` · `David_Gruber` · `David_Saint-Jacques` · `Davis_Submerged_Escape_Apparatus` · `Death_of_Bradley_Westell` · `Death_of_Steve_Irwin` · `Deborah_Andollo` · `Decantation` · `Decima_Flottiglia_MAS` · `Decompression_(diving)` · `Decompression_equipment` · `Decompression_illness` · `Decompression_practice` · `Decompression_sickness` · `Decompression_tables` · `Decompression_theory` · `Deep-sea_exploration` · `Deep-submergence_rescue_vehicle` · `Deep-submergence_vehicle` · `Deep_Drone` · `Deep_diving` · `Deepsea_Challenger` · `Defence_Diving_School` · `Defense_against_swimmer_incursions` · `Demand_valve_oxygen_therapy` · `Deon_Dreyer` · `Department_of_Employment_and_Labour` · `Depth_gauge` · `Devrim_Cenk_Ulusoy` · `Dewey_Smith` · `Diamond_Reef_System` · `Dick_Rutkowski` · `Distance_line` · `Dive_Xtras` · `Dive_boat` · `Dive_briefing` · `Dive_center` · `Dive_computer` · `Dive_leader` · `Dive_light` · `Dive_log` · `Dive_planning` · `Divemaster` · `Diver's_pump` · `Diver_communications` · `Diver_detection_sonar` · `Diver_down_flag` · `Diver_navigation` · `Diver_organisations` · `Diver_propulsion_vehicle` · `Diver_rescue` · `Diver_training` · `Diver_training_organization` · `Diver_training_standard` · `Diver_trim` · `Divers_Academy_International` · `Divers_Alert_Network` · `Divers_Institute_of_Technology` · `Diversnight` · `Divex` · `Diving_Diseases_Research_Centre` · `Diving_Medical_Advisory_Council` · `Diving_Science_and_Technology` · `Diving_Unlimited_International` · `Diving_activities` · `Diving_air_compressor` · `Diving_bell` · `Diving_chamber` · `Diving_cylinder` · `Diving_disorders` · `Diving_equipment` · `Diving_hazards` · `Diving_helmet` · `Diving_in_Timor-Leste` · `Diving_in_the_Maldives` · `Diving_in_the_Philippines` · `Diving_instructor` · `Diving_mask` · `Diving_medicine` · `Diving_physics` · `Diving_procedures` · `Diving_rebreather` · `Diving_reflex` · `Diving_regulations` · `Diving_regulator` · `Diving_safety` · `Diving_safety_officer` · `Diving_shot` · `Diving_suit` · `Diving_supervisor` · `Diving_support_equipment` · `Diving_support_vessel` · `Diving_team` · `Diving_watch` · `Diving_weighting_system` · `Doing_It_Right_(scuba_diving)` · `Dominic_Landucci` · `Dorothy_Metcalf-Lindenburger` · `Dottie_Frazier` · `Doug_Allan` · `Douglas_H._Wheelock` · `Downline_(diving)` · `Drift_diving` · `Drill_Master_diving_accident` · `Drowning` · `Dry_Combat_Submersible` · `Dry_suit` · `Duty_of_care` · `Dynamic_apnea` · `Dysbaric_osteonecrosis` · `Dysbarism` · `E._Lee_Spence` · `E._Yale_Dawson` · `ENOS_Rescue-System` · `Ear_clearing` · `Eduard_Admetlla_i_Lázaro` · `Edward_D._Thalmann` · `Electro-galvanic_oxygen_sensor` · `Elihu_Thomson` · `Elisabeth_Kristoffersen` · `Emergency_ascent` · `Emergency_locator_beacon` · `Emma_Farrell_(freediver)` · `Emma_Hwang` · `Environmental_impact_of_recreational_diving` · `Enzo_Maiorca` · `Equivalent_air_depth` · `Equivalent_narcotic_depth` · `Eric_Cheng` · `Ernest_William_Moir` · `Esbjörn_Svensson` · `Escape_trunk` · `Eugenie_Clark` · `European_Diving_Technology_Committee` · `European_Underwater_Federation` · `European_Underwater_and_Baromedical_Society` · `FNRS-2` · `FNRS-3` · `Faber_Industrie_S.p.A.` · `Fabien_Cousteau` · `Fatma_Uruk` · `Federación_Española_de_Actividades_Subacuáticas` · `Federazione_Italiana_Attività_Subacquee` · `Felix_Hoppe-Seyler` · `Fenzy` · `Fernando_Garfella_Palmer` · `Finger_Lakes_Underwater_Preserve_Association` · `Finning_techniques` · `Finswimming` · `First_aid` · `Fitness_to_dive` · `Flavia_Eberhard` · `Francis_P._Hammerberg` · `Francisco_Ferreras` · `François_de_Roubaix` · `Fred_M._Roberts` · `Freediving` · `Freediving_blackout` · `Freeflow` · `Frenzel_maneuver` · `Frogman` · `Frogman_Corps_(Denmark)` · `Fuerzas_Especiales` · `Fukuryu` · `Full-face_diving_mask` · `Fédération_Française_d'Études_et_de_Sports_Sous-Marins` · `GRUMEC` · `Garrett_Reisman` · `Gary_Gentile` · `Gas_blending` · `Gas_blending_for_scuba_diving` · `George_Bass_(archaeologist)` · `George_F._Bond` · `George_R._Fischer` · `Georges_Beuchat` · `Giovanni_Alfonso_Borelli` · `Global_Explorer_ROV` · `Global_Underwater_Explorers` · `Glossary_of_underwater_diving_terminology` · `Goldfinder` · `Goldfish-class_ROUV` · `Goran_Čolak` · `Gordon_Smith_(inventor)` · `Graham's_law` · `Graham_Balcombe` · `Graham_Jessop` · `Green_Fins` · `Gregory_Chamitoff` · `Guillaume_Néry` · `Gunter_Schöbel` · `Guy_Garman` · `Guybon_Chesney_Castell_Damant` · `Gyrojet` · `HMS_Challenger_(K07)` · `HMS_Royal_George_(1756)` · `Haenyeo` · `Halcyon_PVR-BASC` · `Halcyon_RB80` · `Haldane's_decompression_model` · `Hannes_Keller` · `Hans_Hass` · `Hans_Hass_Award` · `Hawaiian_sling` · `Hazard_analysis` · `Hazmat_diving` · `Health_and_Safety_Executive` · `Heckler_&_Koch_P11` · `Heidemarie_Stefanyshyn-Piper` · `Heinke_(diving_equipment_manufacturer)` · `HeinrichsWeikamp` · `Helgoland_Habitat` · `Helicopter_Aircrew_Breathing_Device` · `Heliox` · [[Helium]] · `Helium_analyzer` · `Helium_release_valve` · `Helix_Energy_Solutions_Group` · `Henry_Fleuss` · `Henry_Valence_Hempleman` · `Henry_Way_Kendall` · `Herbert_Nitsch` · `Hervé_Stevenin` · `Hierarchy_of_hazard_controls` · `High-pressure_nervous_syndrome` · `Hillary_Hauser` · `History_of_Diving_Museum` · `History_of_decompression_research_and_development` · `History_of_scuba_diving` · `History_of_underwater_diving` · `Honor_Frost` · `Hopcalite` · `Hot_stab` · `Hugh_Bradner` · `Human_factors_in_diving_equipment_design` · `Human_factors_in_diving_safety` · `Human_torpedo` · `Hydreliox` · `Hydrogen_narcosis` · `Hydrostatic_test` · `Hydrox_(breathing_gas)` · `Hyperbaric_evacuation_and_rescue` · `Hyperbaric_medicine` · `Hyperbaric_nursing` · `Hyperbaric_stretcher` · `Hyperbaric_treatment_schedules` · `Hyperbaric_welding` · `Hypercapnia` · `Hyperoxia` · `Hyperthermia` · `Hypocapnia` · `Hypothermia` · `IDA71` · `Ian_Edward_Fraser` · `Ice_diving` · `Ictineu_3` · `In-water_recompression` · `In-water_surface_cleaning` · `Incident_pit` · `Incompetence` · `Index_of_recreational_dive_sites` · `Index_of_underwater_divers` · `Index_of_underwater_diving` · `Inner_ear_decompression_sickness` · `Innes_McCartney` · `Instinctive_drowning_response` · `International_Association_for_Handicapped_Divers` · `International_Association_of_Nitrox_and_Technical_Divers` · `International_Diving_Regulators_and_Certifiers_Forum` · `International_Diving_Schools_Association` · `International_Life_Saving_Federation` · `International_Marine_Contractors_Association` · `International_Scuba_Diving_Hall_of_Fame` · `International_Submarine_Escape_and_Rescue_Liaison_Office` · `Interspiro_DCSC` · `Introductory_diving` · `Investigation_of_diving_accidents` · `Isobaric_counterdiffusion` · `Israeli_Diving_Federation` · `Ivan_Tors` · `J._Lamar_Worzel` · `JAGO_(German_research_submersible)` · `JIM_suit` · `Jack_Sheppard_(cave_diver)` · `Jackstay` · `Jacques_Cousteau` · `Jacques_Mayol` · `Jacques_Triger` · `Jagdkommando` · `James_Cameron` · `James_F._Cahill` · `James_Joseph_Magennis` · `James_P._Delgado` · `James_Talacek` · `Jarrod_Jablonski` · `Jason_deCaires_Taylor` · `Jean-Michel_Cousteau` · `Jeanette_Epps` · `Jeffrey_Bozanic` · `Jeffrey_Williams_(astronaut)` · `Jeremy_Hansen` · `Jerónimo_de_Ayanz_y_Beaumont` · `Jessica_Meir` · `Jiaolong_(submersible)` · `Jill_Heinerth` · `Jim_Bowden_(diver)` · `Jim_Jones_(American_football,_born_1935)` · `Joachim_Wendler` · `Job_safety_analysis` · `Jochen_Hasenmayer` · `Joe_Savoie` · `John_Bennett_(diver)` · `John_Bevan_(diver)` · `John_Chatterton` · `John_Christopher_Fine` · `John_D._Craig` · `John_D._Olivas` · `John_Day_(carpenter)` · `John_Deane_(inventor)` · `John_Ernest_Williamson` · `John_Herrington` · `John_Lethbridge` · `John_Mattera` · `John_Morgan_Wells` · `John_Peter_Oleson` · `John_R._Clarke_(scientist)` · `John_Rawlins_(Royal_Navy_officer)` · `John_Scott_Haldane` · `John_Veltri` · `John_Volanthen` · `Johnson_Outdoors` · `Johnson_Sea_Link_accident` · `Jon_Lindbergh` · `Jonathan_Bird` · `Jonathan_Dory` · `Josef_Schmid_(flight_surgeon)` · `Josef_Velek` · `Joseph-Martin_Cabirol` · `Joseph_B._MacInnis` · `Joseph_M._Acaba` · `Joseph_Salim_Peress` · `José_M._Hernández` · `Justin_Brown_(aquanaut)` · `K._Megan_McArthur` · `KOPASKA` · `Kaikō_ROV` · `Karen_Kohanowich` · `Karen_Nyberg` · `Karl_Heinrich_Klingert` · `Karol_Meyer` · `Karst_Underwater_Research` · `Kate_Middleton_(free-diver)` · `Kateryna_Sadurska` · `Kathleen_Rubins` · `Kaşif_ROUV` · `Keith_Jessop` · `Kenneth_William_Donald` · `Kimiya_Yui` · `Kirsty_MacColl` · `Kjell_N._Lindgren` · `Koichi_Wakata` · `Konsul-class_submersible` · `Kronan_(ship)` · `Krzysztof_Starnawski` · `LR5` · `LR7` · `La_Belle_(ship)` · `Lambertsen_Amphibious_Respiratory_Unit` · `Laryngospasm` · `Leigh_Bishop` · `Leni_Riefenstahl` · `Leonardo_D'Imporzano` · `Les_Kaufman` · `Life-support_system` · `Lifting_bag` · `Limpet_mine` · `Line_marker` · `Lionel_Crabb` · `List_of_Divers_Alert_Network_publications` · `List_of_diver_certification_organizations` · `List_of_diving_environments_by_type` · `List_of_diving_equipment_manufacturers` · `List_of_diving_hazards_and_precautions` · `List_of_legislation_regulating_underwater_diving` · `List_of_military_diving_units` · `List_of_researchers_in_underwater_diving` · `List_of_signs_and_symptoms_of_diving_disorders` · `List_of_wreck_diving_sites` · `Liv_Philip` · `Liveaboard` · `Lockout–tagout` · `London_Diving_Chamber_Dive_Lectures` · `Louis_Boutan` · `Louis_de_Corlieu` · `Low_impact_diving` · `Loïc_Leferme` · `Luca_Parmitano` · `Luis_Marden` · `Lyons_Maritime_Museum` · `Lyuba_Ognenova-Marinova` · `MARCOS` · `MSM-1` · `Magnesium_torch` · `Man_in_the_Sea_Museum` · `Mandy-Rae_Cruickshank` · `Marc_Reagan` · `Mares_(scuba_equipment)` · `Margaret_Rule` · `Marine_Commandos` · `Marine_Raider_Regiment` · `Marine_construction` · `Marinejegerkommandoen` · `Mark_Ellyatt` · `Mark_Hulsbeck` · `Mark_IV_Amphibian` · `Mark_M._Newell` · `Mark_T._Vande_Hei` · `Martyn_Farr` · `Mary_Bonnin` · `Mary_Rose` · `Master_Scuba_Diver` · `Master_diver_(United_States_Navy)` · `Matthias_Maurer` · `Maurice_Fargues` · `Maurice_Fernez` · `Maximum_operating_depth` · `McCann_Rescue_Chamber` · `Mechanism_of_diving_regulators` · `Media_diving` · `Mehgan_Heaney-Grier` · `Membrane_gas_separation` · `Mendel_L._Peterson` · `Mensun_Bound` · `Messenger_line` · `Metre_sea_water` · `Michael_Arbuthnot` · `Michael_Barratt_(astronaut)` · `Michael_Board` · `Michael_C._Barnette` · `Michael_Fincke` · `Michael_L._Gernhardt` · `Michael_López-Alegría` · `Michele_Westmorland` · `Middle_ear_barotrauma` · `Milan_Dufek` · `Military_diving` · `Minedykkerkommandoen` · `Minentaucher` · `Mini_Rover_ROV` · `Mir_(submersible)` · `Mission_31` · `Mk_1_Underwater_Defense_Gun` · `Modulated_ultrasound` · `Molecular_sieve` · `Momsen_lung` · `Monofin` · `Monty_Halls` · `Moon_pool` · `Morse_Diving` · `Motion_sickness` · `Motorised_Submersible_Canoe` · `Muck_diving` · `Muscle_memory` · `Myriam_Seco` · `Mystic-class_deep-submergence_rescue_vehicle` · `NATO_Submarine_Rescue_System` · `NOAA_Diving_Manual` · `NOGI_Awards` · `Namibian_Marine_Corps` · `Natalia_Molchanova` · `Nataliia_Zharkova` · `National_Academy_of_Scuba_Educators` · `National_Association_of_Underwater_Instructors` · `National_Board_of_Diving_and_Hyperbaric_Medical_Technology` · `National_Oceanic_and_Atmospheric_Administration` · `National_Speleological_Society` · `Nautical_Archaeology_Program` · `Nautical_Archaeology_Society` · `Nautile` · `Nautilus_Productions` · `Naval_Air_Command_Sub_Aqua_Club` · `Naval_Diving_Unit_(Singapore)` · `Naval_Service_Diving_Section` · `Naval_Special_Operations_Command` · `Naval_Submarine_Medical_Research_Laboratory` · `Naval_Support_Activity_Panama_City` · `Navy_diver_(United_States_Navy)` · `Neal_W._Pollock` · `Necker_Nymph` · `Nederlandse_Onderwatersport_Bond` · `Nemrod` · `Neutral_Buoyancy_Laboratory` · `Neutral_Buoyancy_Simulator` · `Neutral_buoyancy` · `Neutral_buoyancy_pool` · `Neutral_buoyancy_simulation_as_a_training_aid` · `Neville_Coleman` · `Newtsuit` · `Nicholas_Mevoli` · `Nicholas_Patrick` · `Nicole_Stott` · `Night_diving` · `Nikonos` · [[Nitrogen]] · [[Nitrogen_narcosis]] · `Nitrox` · `No-limits_apnea` · `Noel_Monkman` · `Non-freezing_cold_injury` · `Nondestructive_testing` · `Nordic_Deep` · `Norishige_Kanai` · `Nuno_Gomes_(diver)` · `Occupational_safety_and_health` · `Ocean_current` · `Oceanic_Worldwide` · `Octopus_wrestling` · `Offshore_construction` · `Open-water_diving` · `OpenROV` · `Open_Water_Diver` · `Operational_Diving_Division_(SA_Navy)` · `Operations_manual` · `Orinasal_mask` · `Oscar_Gugen` · `Outline_of_recreational_dive_sites` · `Outline_of_underwater_divers` · `Outline_of_underwater_diving` · `Overconfidence_effect` · `Overlearning` · [[Oxygen]] · `Oxygen_compatibility` · `Oxygen_therapy` · `Oxygen_toxicity` · `Oxygen_window` · `Panic` · `Partial_pressure` · `Pascal_Bernabé` · `Patrick_Musimu` · `Paul_Bert` · `Paul_Hill_(flight_director)` · `Paul_Rose_(TV_presenter)` · `Pearl_hunting` · `Pearling_in_Western_Australia` · `Pedro_Duque` · `Peggy_Whitson` · `Penetration_diving` · `Peppo_Biscarini` · `Performance_Freediving_International` · `Pete_Oxford` · `Peter_B._Bennett` · `Peter_Gimbel` · `Peter_Kreeft_(diver)` · `Peter_Scoones` · `Peter_Throckmorton` · `Philippe_Cousteau` · `Philippe_Diolé` · `Philippe_Tailliez` · `Physiology_of_decompression` · `Pierre-Marie_Touboulic` · `Pierre_Frolla` · `Pierre_Petit_(photographer)` · `Pigging` · `Pilar_Luna` · `Pisces-class_deep_submergence_vehicle` · `Polespear` · `Police_diving` · `Pony_bottle` · `Porpoise_(scuba_gear)` · `Potable_water_diving` · `PowerSwim` · `Powerhead_(firearm)` · `Pressure` · `Pressure_swing_adsorption` · `Pressure_washing` · `Priz-class_deep-submergence_rescue_vehicle` · `Professional_Association_of_Diving_Instructors` · `Professional_Diving_Instructors_Corporation` · `Professional_Technical_and_Recreational_Diving` · `Professional_diving` · `Public_safety_diving` · `Pyle_stop` · `QBS-06` · `Queen_Anne's_Revenge` · `Quintana_Roo_Speleological_Survey` · `R-2_Mala-class_swimmer_delivery_vehicle` · `RMS_Lusitania` · `ROV_KIEL_6000` · `ROV_PHOCA` · `RV_Calypso` · `Raid_on_Alexandria_(1941)` · `Ramón_Bravo` · `Randolph_Bresnik` · `Ratio_decompression` · `Rebreather_Association_of_International_Divers` · `Rebreather_diving` · `Recreational_Dive_Planner` · `Recreational_dive_sites` · `Recreational_diver_course_referral` · `Recreational_diver_training` · `Recreational_diving` · `Recreational_scuba_certification_levels` · `Reduced_gradient_bubble_model` · [[Redundancy_(engineering)]] · `Reef_Check` · `Reef_Life_Survey` · `Reid_Wiseman` · `Remotely_operated_underwater_vehicle` · `René_Cavalero` · `Rescue_Diver` · `Rex_J._Walheim` · `Ric_Frazier` · `Ricardo_Armbruster` · `Richard_Harris_(anaesthetist)` · `Richard_Pyle` · `Richard_R._Arnold` · `Richie_Kohler` · `Rick_Stanton` · `Risk_assessment` · `Risk_control` · `Risk_management` · `Rob_Stewart_(filmmaker)` · `Robert_A._Barth` · `Robert_Ballard` · `Robert_Boyle` · `Robert_Croft_(diver)` · `Robert_F._Marx` · `Robert_Sheats` · `Robert_Sténuit` · `Robert_Thirsk` · `Robert_William_Hamilton_Jr.` · `Robin_Cook_(American_novelist)` · `Rodney_Fox` · `Ron_Taylor_(diver)` · `Ronald_J._Garan_Jr.` · `Royal_Australian_Navy_School_of_Underwater_Medicine` · `Royal_Engineers` · `Royal_Navy_ships_diver` · `Rubicon_Foundation` · `Rule_of_thirds_(diving)` · `Russian_commando_frogmen` · `Russian_deep_submergence_rescue_vehicle_AS-28` · `Russian_submarine_AS-34` · `Russian_submarine_Losharik` · `SEALAB` · `SEAL_Delivery_Vehicle` · `SJT-class_ROUV` · `SP-350_Denise` · `SPP-1_underwater_pistol` · `SRV-300` · `SS_Commodore` · `SS_Egypt` · `SS_Laurentic_(1908)` · `Safety-critical_system` · `Safety_data_sheet` · `Salt_water_aspiration_syndrome` · `Salvage_diving` · `Samir_Alhafith` · `Sandra_Magnus` · `Sappers_Divers_Group` · `Sara_Campbell` · `Satoshi_Furukawa` · `Saturation_diving` · `Saturation_diving_system` · `Save_Ontario_Shipwrecks` · `Science_of_underwater_diving` · `Scientific_diving` · `Scorpio_ROV` · `Scott_Carpenter` · `Scott_Carpenter_Space_Analog_Station` · `Scott_Kelly_(astronaut)` · `Scuba_Diving_International` · `Scuba_Educators_International` · `Scuba_Schools_International` · `Scuba_cylinder_valve` · `Scuba_diving` · `Scuba_diving_fatalities` · `Scuba_diving_in_the_Cayman_Islands` · `Scuba_diving_therapy` · `Scuba_diving_tourism` · `Scuba_gas_management` · `Scuba_gas_planning` · `Scuba_manifold` · `Scuba_set` · `Scuba_skills` · `SeaKeys` · `SeaPerch` · `Sea_Dragon-class_ROV` · `Sea_Pole-class_bathyscaphe` · `Sea_Research_Society` · `Seabed_mining` · `Seabed_tractor` · `Seafox_drone` · `Serena_Auñón-Chancellor` · `Shadow_Divers` · `Shallow_Water_Combat_Submersible` · `Shannon_Walker` · `Shark_tourism` · `Shayetet_13` · `Shearwater_Research` · `Sheck_Exley` · `Ships_husbandry` · `Sidemount_diving` · `Siebe_Gorman` · `Siebe_Gorman_CDBA` · `Siebe_Gorman_Salvus` · `Silica_gel` · `Silt_out` · `Siluro_San_Bartolomeo` · `Simon_Mitchell` · `Simone_Arrigoni` · `Simone_Melchior` · `Single_point_of_failure` · `Sinking_of_MV_Conception` · `Sinking_of_the_Rainbow_Warrior` · `Sinking_ships_for_wreck_diving_sites` · `Situation_awareness` · `Skandalopetra_diving` · `Skill_assessment` · `Snorkel_(swimming)` · `Snorkeling` · `Snuba` · `Society_for_Underwater_Historical_Research` · `Society_for_Underwater_Technology` · `Solo_diving` · `Sonar` · `South_African_Underwater_Sports_Federation` · `South_Pacific_Underwater_Medicine_Society` · `Space_Systems_Laboratory_(Maryland)` · `Spearfishing` · `Speargun` · `Special_Actions_Detachment` · `Special_Air_Service` · `Special_Air_Service_Regiment` · `Special_Boat_Service` · `Special_Boat_Squadron_(Sri_Lanka)` · `Special_Forces_Command_(Turkey)` · `Special_Forces_Group_(Belgium)` · `Special_Operations_Battalion_(Croatia)` · `Special_Service_Group_(Navy)` · `Special_Warfare_Diving_and_Salvage` · `Sponge_diving` · `Sport_diving_(sport)` · `Stan_Waterman` · `Standard_diving_dress` · `Standard_operating_procedure` · `Star_Canopus_diving_accident` · `Static_apnea` · `Steinke_hood` · `Stena_Seaspread_diving_accident` · `Stephanie_Schwabe` · `Stephen_Frink` · `Stephen_Keenan` · `Steve_Chappell` · `Steve_Irwin` · `Steve_Lewis_(diver)` · `Steve_Parish_(photographer)` · `Steve_Squyres` · `Stig_Severinsen` · `Stress_exposure_training` · `Stéphane_Mifsud` · `Sub-Aqua_Association` · `Sub_Marine_Explorer` · `Submarine_Escape_Immersion_Equipment` · `Submarine_Escape_Training_Facility_(Australia)` · `Submarine_Escape_and_Rescue_system_(Royal_Swedish_Navy)` · `Submarine_Products` · `Submarine_Rescue_Diving_Recompression_System` · `Submarine_escape_training_facility` · `Submarine_pipeline` · `Submarine_rescue` · `Submarine_rescue_ship` · `Subskimmer` · `Sunita_Williams` · `Supervised_diver` · `Surface-supplied_diving` · `Surface-supplied_diving_equipment` · `Surface-supplied_diving_skills` · `Surface_marker_buoy` · `Surfer's_ear` · `Sustained_load_cracking` · `Suunto` · `Swedish_warship_Mars` · `Swietenia_Puspa_Lestari` · `Swimfin` · `Swimming-induced_pulmonary_edema` · `Swimming_at_the_1900_Summer_Olympics_–_Men's_underwater_swimming` · `Sydney_Knowles` · `Sylvia_Earle` · `T1200_Trenching_Unit` · `Tactical_Divers_Group` · `Takuya_Onishi` · `Tamara_Benitez` · `Tanya_Streeter` · `Tara_Ruttley` · `Taravana` · `Task_loading` · `Teaching_method` · `Technical_Diving_International` · `Technical_diving` · `Ted_Eldred` · `Tektite_habitat` · `Teseo_Tesei` · `Testing_and_inspection_of_diving_cylinders` · `Thalmann_algorithm` · `Tham_Luang_cave_rescue` · `The_Darkness_Beckons` · `The_Diver` · `The_Last_Dive` · `The_Silent_World:_A_Story_of_Undersea_Discovery_and_Adventure` · `Thermal_balance_of_the_underwater_diver` · `Thermal_conduction` · `Thermal_lance` · `Thermodynamic_model_of_decompression` · `Thomas_Marshburn` · `Thomas_Pesquet` · `Tim_Peake` · `Timeline_of_diving_technology` · `Timothy_Creamer` · `Timothy_J._Broderick` · `Timothy_Kopra` · `Tom_Mount` · `Tom_Sietas` · `Torricellian_chamber` · `Towboard` · `Tremie` · `Trevor_Hampton` · `Trevor_Jackson_(diver)` · `Trimix_Scuba_Association` · `Turkish_Underwater_Sports_Federation` · `U.S._Navy_Diving_Manual` · `UNGERIN` · `URF_(Swedish_Navy)` · `USS_Monitor` · `US_Navy_decompression_models_and_tables` · `Umberto_Pelizzari` · `Uncontrolled_decompression` · `Undersea_and_Hyperbaric_Medical_Society` · `Underwater_Archaeology_Branch,_Naval_History_&_Heritage_Command` · `Underwater_Bike_Race` · `Underwater_Construction_Teams` · `Underwater_Demolition_Command` · `Underwater_Demolition_Team` · `Underwater_Escape_Training_Unit` · `Underwater_Hockey_World_Championships` · `Underwater_Orienteering_World_Championships` · `Underwater_Rugby_World_Championships` · `Underwater_Society_of_America` · `Underwater_acoustic_communication` · `Underwater_acoustic_positioning_system` · `Underwater_acoustics` · `Underwater_archaeology` · `Underwater_breathing_apparatus` · `Underwater_computer_vision` · `Underwater_construction` · `Underwater_cutting_and_welding` · `Underwater_cycling` · `Underwater_demolition` · `Underwater_diving` · `Underwater_diving_emergency` · `Underwater_diving_environment` · `Underwater_diving_in_Guam` · `Underwater_domain_awareness` · `Underwater_environment` · `Underwater_exploration` · `Underwater_firearm` · `Underwater_football` · `Underwater_habitat` · `Underwater_hockey` · `Underwater_hockey_in_Australia` · `Underwater_hockey_in_Turkey` · `Underwater_logging` · `Underwater_orienteering` · `Underwater_photography` · `Underwater_photography_(sport)` · `Underwater_rugby` · `Underwater_rugby_in_the_United_States` · `Underwater_search_and_recovery` · `Underwater_searches` · `Underwater_sports` · `Underwater_survey` · `Underwater_target_shooting` · `Underwater_vehicle` · `Underwater_videography` · `Underwater_vision` · `Underwater_work` · `United_Diving_Instructors` · `United_States_Marine_Corps_Combatant_Diver_Course` · `United_States_Marine_Corps_Force_Reconnaissance` · `United_States_Marine_Corps_Reconnaissance_Battalions` · `United_States_Navy_Experimental_Diving_Unit` · `United_States_Navy_SEALs` · `United_States_military_divers` · `Valerie_Taylor_(diver)` · `Valerie_van_Heest` · `Valsalva_maneuver` · `Varying_Permeability_Model` · `Vasa_(ship)` · `Vertical_Blue` · `Victor_Berge` · `VideoRay_UROVs` · `Vintage_scuba` · `Waage_Drill_II_diving_accident` · `Wall_diving` · `Walter_Steyn` · `Water_polo_cap` · `Water_safety` · `Water_surface_searches` · `Welfreighter` · `Western_Norway_University_of_Applied_Sciences` · `Wet_Nellie` · `Wet_sub` · `Wetsuit` · `Whydah_Gally` · `Wildrake_diving_accident` · `Willard_Franklyn_Searle` · `Willful_violation` · `William_Beebe` · `William_Hogarth_Main` · `William_Paul_Fife` · `William_R._Royal` · `William_Stone_(caver)` · `William_Trubridge` · `Women_Divers_Hall_of_Fame` · `Woodville_Karst_Plain_Project` · `Work_of_breathing` · `World_Recreational_Scuba_Training_Council` · `Wreck_diving` · `YMCA_SCUBA_Program` · `Yasemin_Dalkılıç` · `YouTube` · `Yuri_Gagarin_Cosmonaut_Training_Center` · `Yves_Le_Prieur` · `Zale_Parry` · `Émile_Gagnan` · `Épaulard` · `Şahika_Ercümen` > **Room:** [[Helium]] · **Status:** ✅ shipped ## Overview Trimix is a [[Breathing_gas|breathing gas]] mixture used in technical diving composed of three components — oxygen, helium, and nitrogen — formulated to extend safe operating depth beyond the limits of ordinary compressed air. The diluent helium replaces a portion of the nitrogen, reducing the partial pressure of N2 and so mitigating [[Nitrogen_narcosis|nitrogen narcosis]], while the oxygen fraction is reduced below the atmospheric 21% to keep its partial pressure within non-toxic bounds at depth. Mixes are denoted as Trimix X/Y, where X is the percentage of oxygen and Y the percentage of helium, with the remainder being nitrogen; common technical mixes include 21/35, 18/45, 15/55, and 10/70 for progressively deeper dives. Two depth parameters govern mix selection. Maximum Operating Depth (MOD) is set by the working oxygen partial-pressure limit, typically 1.4 bar: MOD = 10 × (ppO2_max / fO2 − 1) metres. Equivalent Narcotic Depth (END) estimates the narcotic load by treating the nitrogen, and sometimes the oxygen, as narcotic and computing the air-depth that would produce the same partial pressure of narcotic gas. Helium's low molecular mass and metabolic inertness sharpen mental performance at depth but accelerate body-heat loss and demand more conservative decompression schedules because of its faster tissue uptake and elimination kinetics. First applied by U.S. Navy diver Max Nohl in 1937 and refined for commercial saturation diving in the 1960s, Trimix is now standard for technical dives below roughly 50 metres, for cave penetration and wreck exploration, and for any operation where ordinary air would be both narcotic and toxic. ## See also - Room hub: [[Helium]] - p5.js Editor conventions: P5 JS EDITOR - Wiki root: MAIN --- *Scaffolded by `generative-microsim` from row 73 of the Helium sheet on 2026-05-12T06:10:05Z.*  *Built to the [[WT!P5_js_Microsim_Master_Class|p5.js Master Class]].*  ## Wikipedia : Wikitube **Strict pair:** [Wikipedia](https://en.wikipedia.org/wiki/Trimix_%28breathing_gas%29) : [Wikitube](https://en.wikitube.io/wiki/Trimix_%28breathing_gas%29) ## Previous hub tags Tree parent: [[Helium]]. Legacy hubs: none. --- *Sources: 1 legacy note. Minted wave 1, 2026-07-30 (v1.6 order).*