For which reason are attached boots designed?

Attached boots on a dry suit are designed primarily to provide insulation. When divers wear attached boots, their feet remain insulated from the cold water because the boots are a part of the suit's waterproof seal, helping to maintain the warmth created by the diver’s body heat. This is crucial for thermal protection during dives in cold environments, where exposure to low water temperatures can lead to hypothermia.

While other features of attached boots may contribute to comfort and mobility, the primary function in the context of a dry suit is indeed to enhance thermal protection. Therefore, the design of attached boots focuses significantly on insulation, ensuring divers remain warm and safe underwater.