Celebrity Beach Bums for National Beach Day!

It's National Beach Day ... and when it comes to the sun, the sand, and the surf ... these sexy celebs can't seem to get enough beach.

Halle Bailey, Darianka, and Bella Thorne all love redefining what it actually means to be a beach bum -- emphasis on bum -- because just look at them! They're definitely in their element.

Camila Cabello's also solidified her beach babe status ... getting wet and wild in this teeny bikini!