Another word: bodysurfing.
Sure, bodysurfing's hydroelectric ocean love jolt is quite enough to send anyone in to paroxyms of rolling joy, but riding the sea's pulse nude will send you over the falls to pure enlightenment. The reason why porpoises seem to have a permanent smile will suddenly become blindingly clear.
It is best to do this at a nude beach, but if you are feeling sufficiently adventurous, any old beach will do. You'll have to take off your trunks or bikini on the beach. Trying to take off said items in the water and then surfing with them in your hand is a surefire way to lose them (trust me). 'Splain that, Lucy! Plus, you won't have as much fun.
Besides the heavenly sensuous benefits of nude bodysurfing, there are practical payoffs. Immediately there is less drag, resulting in quicker takeoffs and better maneuverability. Also, if you are riding the shore break, the sand normally dredged in to your suit suddenly becomes a non-issue.
This is one of the best things you can do naked by yourself. Healthy, clean fun. No associated guilt or harmful byproducts. Give it a try on your next warm free day.