Decompression sickness happens when dissolved nitrogen forms bubbles in your blood and tissues — usually after ascending too fast, skipping stops, or exceeding no-deco limits.
Things that raise risk
- Fast ascents or skipped safety/deco stops
- Repetitive or multi-day diving without enough surface interval
- Dehydration, fatigue, cold, and exertion
- Flying too soon after diving
Warning signs
- Joint or limb pain ('the bends')
- Unusual fatigue, dizziness, or skin rash/marbling
- Numbness, tingling, weakness, or confusion (neurological — urgent)
Symptoms can appear during the dive or hours later. If you suspect DCS, treat it as an emergency — see the first-aid article.