What is the risk if a diver ascends too quickly to the surface after a deep dive?

When a diver ascends too quickly after a deep dive, the primary risk is decompression sickness. This condition occurs because, at depths, a diver's body absorbs nitrogen from the breathing gas under high pressures. As the diver ascends rapidly, the pressure decreases quickly, which can cause the nitrogen that has been absorbed into body tissues to come out of solution, forming bubbles. These bubbles can cause various symptoms, ranging from joint pain and rashes to more severe effects such as neurological issues or even life-threatening conditions.

Decompression sickness, often referred to as "the bends," emphasizes the importance of controlled ascents and safety stops. Proper ascent rates allow nitrogen to be released safely from the body, preventing bubble formation. Factors such as dive duration, depth, and previous dives significantly influence the risk level, making adherence to dive tables and training protocols crucial for diver safety.

Other options, like euphoria, surface respiration, and hypothermia, do not directly relate to the effects of rapid ascents from depth in the same manner as decompression sickness, making them less relevant in this context.