My very favorite beach on Vieques was “Playa Negra,” or Black Sand Beach. When we went, there were only two people there (locals, they know the good beaches)! It’s not the easiest to find, and you have to park on the road and walk about fifteen minutes along a creek bed, but it was well worth it!
My oldest son and I went to the beach because the other two “wanted to relax,” ie, take a nap!
It’s an absolutely beautiful beach!