The closest thing to a beach bar on St Jean would be La Plage restaurant at the Pearl Beach Hotel on St Jean. There’s a free municipal parking lot diagonally across from the hotel. It’s more down to earth than the other party places on St Jean - Nao, Nikki, La Guérite, and Gyp Sea. You would probably like ‘Ti Corail on Grand Cul de Sac, but it is so tiny that getting in there without a reservation is impossible, and the parking is equally impossible.