Muscles!I am mesmerised when I see a man on the beach wearing his Speedos and everything about him is seeable, his muscles and his physique. A fit man is very attractive from some primeval aspects, as well as with modern potential.
With all the diseases there are to cut men down, it is essential they keep superfit, their potency is then very apparent to we girls when we see them on the beach.
Of course, the other part of a man that is so appealing is his penis. I have little experience with variety, but it is true the more a man can stretch our vagina the more pleasure we get, it isn't all in length, but how wide he is!