Dirk Nowitzki Shows Off Shredded Retirement Bod on Vacation in Mexico

Dirk Nowitzki's done playing ... but his body sure as hell didn't get the memo ... 'cause the recently retired NBA superstar ditched his shirt on vacation in Mexico -- and the dude looks jacked!!!

The Dallas Mavericks legend and his wife, Jessica Olsson, hit up the beach in Tulum earlier this week ... makin' a splash and enjoying every bit of the unemployment life.

Dirk's got a LOT to celebrate -- he finished his career as the 6th top scorer to ever play in the league ... and the Mavs' all-time leader in points, rebounds, blocks and games played.

Look, all that is nice and everything ... but the dude should be most proud of his beach bod.

Seriously, did anyone know the dude looked like this with his shirt off???