Why Is Ascent the Most Dangerous Phase of the Dive?
The Question
Why do most blackouts occur near the surface or after surfacing?
Short Answer
Because falling pressure during ascent causes a rapid drop in oxygen partial pressure, even if total oxygen remains unchanged.
Deeper Explanation
(Explain pressure, partial pressure, lung expansion, and delayed effects.)
What This Means for Freedivers
- Slow ascent is not a safety guarantee
- Surface protocols matter
- Post-dive monitoring is essential