New England Patriots tight end Rob Gronkowski is out with a broken arm, but luckily for him he can recover in sunny Florida ... because he recently dropped $1.6 million on a new beachside party pad.

The NFL superstar -- who has a serious reputation for getting loose -- inked a deal to buy the 4,781-square-foot mansion in Tampa just a few months after signing a $54 million extension contract with the Pats.

Gronk's new 4-bedroom, 5-bath crib is a partier's dream. It sports custom built-in fish tanks, primo surround sound for the whole house, three outdoor entertainment areas, infinity pool, spa, and ocean views ... which are sure to impress the ladies.

Of course, Rob needs to do a lil recovering before he can take full advantage -- he just had surgery last Monday to fix his broken forearm.