Jeff Bezos Plays Photog for Bikini-Clad Lauren Sanchez on Superyacht

Jeff Bezos isn't too rich to be a good Instagram photog for his hot fiancée, Lauren Sanchez ... proving as much during an impromptu photo shoot on his superyacht.

The Amazon founder/multi-billionaire was kinda playing the role of head-over-heels simp Monday while aboard his new nautical plaything -- and by that ... we mean he was snapping sexy shots of LS, who was posing for him on the deck of his boat, wearing just a bikini.

When you got a lady as smoking hot as Lauren ... sometimes a gig like this just comes with the territory. At a certain point, ya gotta play photog for your girl -- and Jeff did his part.

As for the shoot itself ... well, it looks like JB was getting Lauren from the front, back, side and just about every other angle as she worked the camera for him. He was just using his camera phone for the pics -- and they might even end up on the 'Gram if we're lucky.

BTW, the soon-to-be-married couple was sailing Jeff's massive $500 million vessel -- which is 417 feet in length, complete with 3 masts -- out in Italy ... off the coast of Portofino, specifically. They landed on the boat via helicopter ... and eventually went jet-skiing.

It's just the latest homage Jeff has made to Lauren ... remember, there's a carved figurehead at the front of this yacht here that's sculpted in the shape of a beautiful woman -- and some see a resemblance to Lauren. Basically, it's possible/likely she was his muse in the art piece.

Now, with him proving to be a reliable partner for social media purposes ... it's full circle.