Kim Kardashian's hanging loose ... surfing manmade waves on a wake surfing adventure -- and, she's got her balance on lock.
The reality television star posted a clip to Instagram ... saying she's taking a lesson with Austin Keen -- a world champion skimboarder and wake surfer.
He's in the back in one of the clips KK posted, shredding the gnar as the two hold onto the boat that's chopping up the water and creating waves for them.
Eventually, they have to let go of their hold on the ski rope .