J Lo's Ex Casper Smart Hits Beach with Hot Chick

Casper Smart doesn't look too busted up about his famous ex-GF's engagement ... he's got his hands full with another smokin' babe!!!

Casper and his new hottie -- a model who goes by the name Coca -- are making waves in Miami, hitting up a beach Monday afternoon for some serious PDA. Casper and his bikini-clad companion were all over each other, sucking face and locking legs in the water. Such a booty-full day!

The couple didn't have a yacht experience, but there was a motorboat sighting. Check out the gallery ... you'll get it.

As you know ... Casper's ex, Jennifer Lopez, just got engaged to retired MLB stud Alex Rodriguez. Casper and J Lo dated for several years before calling it quits in August 2016.

They both quickly moved on, and both seem VERY happy today.

It's like a real life fairy tale ... with more butt cheeks.