Chris Webber -- First Surfing Lesson ... We're Gonna Need a Bigger Board!

NBA legend Chris Webber got his first surf lesson Monday morning, and most importantly ... he actually survived, because he tells TMZ Sports it was "one of the toughest things" he's ever done.

Webber says he randomly met pro surfer Pascal Stansfield while on vacay in Cabo San Lucas, and joked about surfing ... not knowing Stansfield was a pro. Next thing ya know, he's in the middle of a 20-minute first timers sesh.

C-Webb says he did manage to get up on his board multiple times, but never rode a full wave. He added, "I am just so glad there wasn’t a video of me crawling out the water because that was tough."

He's being a little tough on himself -- it's not everyday you see a 6'11" guy shredding waves.