Kendall Jenner doesn't need a bathing suit to go swimming at the beach ... her see-through dress will do just fine.

Kendall was at a beach party with Bella Hadid Sunday on the Greek island of Mykonos, where she decided to take a dip in a transparent black dress ... champagne bottle in hand and all.

Kendall and Bella have been on a bit of a Eurotrip of sorts ... bouncing around from Paris to London for Pride, and now Greece in a matter of about a week.

As for the wardrobe malfunction here, she clearly doesn't seem to mind how tightly the wet dress clings to her body -- and, frankly, neither do we. 

The real question: who's the dude flinging her around? Better call A$AP.

NO SUIT NO PROBLEM
MEGA