The appropriate wetsuit thickness depends primarily on water temperature, dive duration and your personal sensitivity to cold. Thin suits are commonly used in warm tropical water, while cooler conditions require thicker neoprene or additional thermal protection. Because individual comfort varies considerably, local dive conditions should also be considered.

A wetsuit should fit closely against the body without large gaps where water can circulate, but it should not restrict breathing or normal movement. A poor fit can reduce thermal performance, so sizing and body shape are just as important as wetsuit thickness.