What should be done to conserve energy while waiting for rescue in cold water?

To conserve energy while waiting for rescue in cold water, wearing a life jacket to maintain body heat is particularly effective. A life jacket provides buoyancy, allowing you to float without expending unnecessary energy on swimming or staying afloat. This buoyancy means you can conserve your strength and warmth. In cold water, the risk of hypothermia increases significantly, so maintaining body heat becomes crucial.

The design of a life jacket also helps retain heat by preventing excess cold water from circulating around the body. It acts as an insulating layer and can reduce the chances of losing body heat, which is critical for survival until help arrives.

Other methods, although they could theoretically contribute in some way, are not as effective or could be counterproductive in this situation. For instance, swimming dynamically may lead to fatigue and increased heat loss due to more exposure to cold water. Remaining immobile can save energy but is not as effective in preventing heat loss as wearing a life jacket. Continually shouting for rescue may waste energy and increase exposure without significantly aiding in survival compared to the insulation provided by a life jacket.