UFC's Cowboy Cerrone Almost Dies In Cave Diving Incident

UFC legend Donald "Cowboy" Cerrone says he's lucky to be alive after a major disaster during a cave diving excursion in Mexico ... but he told the Grim Reaper, "Not today Mother F**ker!"

Cowboy is an avid diver -- and went to Cozumel to explore some of the underwater caves with a team of scuba divers.

FYI, some of the caves extend about 11 miles inland.

During the dive, Cowboy says he had a "catastrophic worst case scenario" when the gang was caught in a "silt out" ... which is when particles on the sea floor get kicked up, causing ZERO visibility for the divers.

Cerrone says he lost the cave line -- which would have led him out of the cave -- and couldn't find his diving partner.

But, Cowboy kept his composure and ultimately found his way back to safety.

After the incident, Cerrone explained -- "Told the grim reaper 'Not today Mother F**ker' I’m figuring this the f**k out and coming home!!"