How does a wetsuit function to maintain warmth for the diver?

A wetsuit maintains warmth for a diver primarily by trapping a thin layer of water between the diver's skin and the suit. This injured water is warmed by the body's heat, creating an insulating layer that helps to reduce heat loss to the surrounding water. As the water is warmed by the body, it creates a microclimate that can keep the diver comfortable for extended periods.

The design of a wetsuit allows it to fit snugly against the skin, minimizing the flow of cold water into the suit and ensuring that the warm layer of water remains effectively insulated. While the material and fit of the wetsuit contribute to its performance, the primary mechanism by which it provides warmth is through this captured layer of water.