Khloe Kardashian and Tristan Thompson still haven't come up for air ... 'cause they're still sucking face in Mexico with Kendall Jenner and Ben Simmons in tow.
Khloe, Tristan, Kendall, Ben and a bunch of friends hit up the popular resort town of Puerto Vallarta, Mexico where we're certain there's TONS of action ... based on the pics -- a little swimming in the pool, a dip in the ocean, some jet skiing and PDA-packed sessions.
The NBA stars weren't completely tied down .