Justin Bieber -- I'm On a Boat, Bitch!

Justin Bieber has some gall ... having a better 4th than just about any true American ... knocking back a few cold ones on an enormous yacht.

Biebs ... was off the coast of Miami Beach -- shirtless of course -- drinking a frosty Corona on the bow of his rented luxury vessel.

Last time the pop star was in Miami Beach he was busted for DUI ... so this is a safe move unless Biebs takes the helm.

Enjoy your sparklers and frozen hot dogs this weekend.