Contrary to popular belief, the beach is one of the WORST places to have sex. Most people who mention it usually do so because they've never experienced it. I finally tried it out a couple of years ago and in the middle of sex we were VICIOUSLY attacked by sandcrabs. She wanted me to continue anyway, and was all, "it hurts so good!", but even she had to stop after awhile. We spent the next two days treating ourselves from the attacks, lol.
SEX ON THE BEACH = BAD!!!!!