A couple of years ago my partner and I were on holiday at a beach resort in Antigua. One morning I was taking an early morning stroll along the beach and was wearing just a pair of swim shorts. To my surprise I noticed that I was gradually going hard and the bulge in my shorts was becoming more obvious. There were a few people about a hundred yards away so I decided to go into the inviting sea to 'cool off.'
I swam out about thirty yards to where the water was about six inches above my waist and noticed that the water had not removed the erection, if anything I was even harder. Checking there was nobody else near me, I slipped my shorts down to my ankles, freeing my throbbing cock. It felt delightful in the warm water and so I kept my back to the shore and began to caress my cock. I could feel the excitement mounting and my balls tightened as I shot my first load of cum into the sea. Several creamy jets followed as I kept on stroking.
After I had calmed down, I put my shorts back on and returned to the beach where a few more people had gathered to sunbathe but nobody seemed to have noticed. I returned to our apartment where I told my partner about my experience. This resulted in a magnificent screw in the shower, but that is another story. As for masturbating in the sea - all I can say is that it was worth it and I will repeat it given the right set of circumstances.