Khabib Nurmagomedov Swims In Freezing River In Dagestan In Insane Training Video

He's wrestled live bears and sprinted up mountains, but now Khabib Nurmagomedov is taking his training to the next level ... swimming a freezing cold Dagestani river!

Oh, and he's swimming against a pretty strong current!!!

THIS IS INSANE!!

Khabib -- who recently defeated Dustin Poirier -- is gearing up for a tough fight (presumably against Tony Ferguson) and he's not wasting any time getting into fight shape.

Which is why he ended up taking a dip in a river in Kizilyurt -- a small town in Dagestan.

Khabib's pal (who goes by King Farruh) shot the footage and gave his account of the session.

"Hard work and dedication from champ khabib_nurmagomedov. Today was very cold, he doesn’t care."

"Water was very cold I tried to put my feet and almost freeze my a$$ off. Tony you’re in trouble!"