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 seriously 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 po...