You develop a cramp while swimming. Which of the following actions should you take?

When experiencing a cramp while swimming, drawing your knees towards your chest and massaging the affected muscle is the most effective action to take. This technique helps to stretch the cramped muscle and relieve tension. By bending your knees, you reduce strain on the muscle and facilitate blood flow, which can alleviate the cramping sensation. Massaging the area can also assist in loosening the muscle fibers and promoting relaxation.

While other options may seem plausible, they are less effective in this particular situation. Attempting to swim to shore may exacerbate the cramp or lead to fatigue, especially if the cramping is severe. Floating on your back and calling for help could be sensible in emergencies, but it does not address the cramp itself, which may require immediate relief. Drinking water is essential for hydration, particularly in a swimming environment, but it does not provide direct relief from muscular cramps. Thus, focusing on muscle recovery through stretching and massage is the best approach when dealing with a cramp while in the water.