Sydney Sweeney Rides Jet Ski on Lake With Mystery Man Wrapped Around Her

Sydney Sweeney is turning up the summer heat ... riding a Sea-Doo with a new muscular man holding her waist.

The actress was all smiles Friday during her thrilling ride -- grinning ear to ear with her unidentified hunk in tow.

Safety came first for the cuddly duo, both rocking life vests as they zipped across the water.

The fun didn't stop there ... Sweeney was seen launching herself off a cliff and rope-swinging straight into the lake, somewhere in Idaho.

When she wasn't in the water, SS was seen strutting around in a tight navy blue one-piece swimsuit and some sleek sunglasses.

While it's unclear what the relationship is with her new dude, Sydney's been enjoying single life after calling it quits with her ex-fiancé Jonathan Davino.