YouDive educational guide · References checked 30 September 2026 · Independent instructor and medical review pending. This library does not provide certification, individual medical clearance or a dive plan.
Understand the risk
The oxygen fraction and chosen oxygen partial-pressure limit determine an oxygen-related depth boundary. Other limits may require a shallower dive. Training, experience, narcosis, workload and decompression still apply.
Maximum operating depth is a boundary: what connects
Gas boundary
Oxygen-related limit
- Verify from analysed contents
Training boundary
Your certification and skills
- May be shallower
Conditions
Actual workload and control
- May require a simpler dive
Concept relationships from this lesson. These are discussion points, not a dive profile or emergency treatment sequence. Read the cited sources; qualified review is pending.
Put the knowledge into practice
Calculate and verify gas limits during formal training and use a clear identification system. A cylinder marking needs to agree with its analysed contents. Plan margin for imperfect buoyancy and conditions rather than hovering at a theoretical maximum.
What to notice and discuss
| Consider | Why it matters | Planning or learning response |
|---|---|---|
| Gas boundary | Oxygen-related limit | Verify from analysed contents |
| Training boundary | Your certification and skills | May be shallower |
| Conditions | Actual workload and control | May require a simpler dive |
PAUSE & THINK
What would you do?
A wall drops below the depth suitable for your gas.
Reveal the discussion answer
Plan a route and depth with margin; the attraction below does not change the gas limit.
Frequently asked questions
Is MOD the only depth limit that matters?
No. Use the most restrictive applicable boundary and consider whether the dive is suitable at all.
Sources & further reading
DAN: Oxygen toxicity ↗DAN: Insufficient dive planning ↗These sources inform this guide; their organisations have not reviewed or endorsed YouDive.
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