The hazard list is short and stubborn: hypoxia, equalisation injury, boats, and the social pressure to go again. This is orientation, not a treatment guide.
If a sentence here sounds like a rule, it is a culture rule, not a statute everywhere.
Hazards
- Hypoxic blackout — The headline hazard.
- Loss of motor control at the surface — A warning state courses treat as an emergency.
- Equalisation damage — Ears, sinuses, and the rare worse case — clinicians, not blogs.
- Boat strike — Long invisibility.
- Cold-water exit collapse — Afterdrop and poor decisions on the rocks.
- Solo depth and solo spear — The pattern in the obituaries.
Rules
- No solo depth — The rule this atlas will repeat.
- No hyperventilation games — Including “just a little.”
- One safety per diver in the water at depth — Or a taught team system, not a crowd of photographers.
- End after a warning — The day has a stop button.
- Emergency services over folklore — Especially if the person is not clearly themselves.
Red flags
- Anyone selling a guaranteed depth on day one — Walk.
- A partner who is filming the personal best — Stop the dive.
- Confusion, pale face, or a delayed answer at the surface — Emergency path, not a joke.
- Alcohol “to relax” before apnea — The session is cancelled.
First response
- Call emergency services and use taught course skills — This atlas will not write a rescue sequence that people might follow instead of a class.
- Keep the person at the surface with a float if trained to — Untrained heroics add casualties.
- Not medical advice — Blackout aftercare is clinical.
The red flags are social. The first response is a phone and a course you already took.