Manu Ginobili Saves Woman Who Fell On Sand Dune in Argentina

Manu Ginobili has turned into a straight-up SUPERHERO in retirement ... 'cause the NBA legend sprang into action and helped rescue a grandma who fell down a sand dune!

Here's what went down ... Twitter user @almumansi (who goes by AM) says her grandmother was at the beach in Blanca Bay, Argentina when she decided to try to climb a sand dune, but fell.

That's when 2 men -- including 42-year-old Manu -- sprinted to help the lady, picked her up and carried her to safety.

AM says by the time she got to the scene, she noticed her grandma was taking a pic with one of the heroes ... and realized it was MANU FREAKIN' GINOBILI!!!

Of course, Manu is from Argentina and spends a lot of time in his home country during retirement.

Ginobili was a helluva ballplayer during his career ... and is a shoo-in for the basketball Hall of Fame. But, stories like this are much better than any highlight on the court.