“Diving well means understanding what your body is doing beneath the surface — and respecting the physics that govern every ascent.”
Decompression Sickness Explained: What Every Diver Should Know
Decompression sickness — commonly called “the bends” — is a medical condition that can occur when a diver ascends too quickly after spending time at depth. It is serious, treatable when caught early, and largely preventable with proper training, planning, and responsible diving practice. Understanding how it works is not just academic: it is a fundamental part of dive safety that every person who enters the water with a tank should know.
How Decompression Sickness Occurs
When you dive, the increased pressure at depth causes nitrogen from your breathing gas to dissolve into your blood and body tissues at a higher rate than at the surface. This is normal and harmless while you remain at depth. The problem arises when you ascend too quickly — if you rise faster than your body can safely off-gas the dissolved nitrogen, it can form bubbles in your tissues, joints, and bloodstream. These bubbles cause the symptoms of decompression sickness, which range from mild joint pain to neurological symptoms in severe cases.
Symptoms
The symptoms of decompression sickness typically appear within 24 hours of a dive — often within the first six hours. They include joint pain (particularly in the shoulders, elbows, knees, and hips), skin rashes or mottling, fatigue, dizziness, numbness or tingling, difficulty breathing, and in severe cases, paralysis or loss of consciousness. The appearance of any neurological symptoms should be treated as a medical emergency. Any suspected case of decompression sickness requires immediate medical assessment.
Treatment
The primary treatment for decompression sickness is hyperbaric oxygen therapy — a process in which the affected person breathes pure oxygen inside a pressurised chamber. This reduces bubble size and accelerates the elimination of dissolved nitrogen from the tissues. The nearest hyperbaric facility to the Great Barrier Reef is located in Cairns, with additional facilities in Townsville. First aid for suspected decompression sickness includes 100% oxygen and immediate contact with emergency services or the Divers Alert Network (DAN).
Prevention
Decompression sickness is almost entirely preventable through proper diving practice. This includes: following no-decompression limits for each depth; making slow, controlled ascents; performing safety stops at 5 metres for three to five minutes; avoiding repetitive deep dives in quick succession; staying well hydrated; and avoiding flying within 18 to 24 hours of diving. All reputable dive operators on the Great Barrier Reef brief their divers on safe ascent practices before every dive.
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FAQs
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