What is the primary purpose of an exposure suit while diving?

The primary purpose of an exposure suit while diving is to preserve body heat. These suits are designed to provide thermal insulation, which is crucial for maintaining a diver's core body temperature, especially in cooler water conditions. When submerged, the body's heat can be rapidly lost to the surrounding water, leading to hypothermia if proper thermal protection is not worn. Exposure suits come in various forms, including wetsuits and drysuits, each offering different levels of thermal protection depending on the water temperature and conditions.

By effectively trapping a thin layer of water between the suit and the skin, wetsuits can help keep the diver warm as the body heats this water. Dry suits, by creating an air pocket that insulates the diver from the water, provide an even greater level of thermal protection, making them suitable for colder environments.

While the other options may address aspects of diving gear, they do not align with the primary function of exposure suits. Enhancing buoyancy or providing additional weight could lead to incorrect buoyancy control underwater and would not assist in retaining heat. Increasing underwater visibility is typically achieved through proper mask design or lighting rather than through an exposure suit.