Matt Damon Shows Off Rock Hard Abs on Boat During Italian Vacation

Matt Damon got into the best shape of his life for "The Odyssey" -- and he wasn’t about to just flush all that hard work on set ... 'cause he was in full shirtless mode during some well-earned downtime too.

Take a good ol' look -- Matt and his chiseled abs were showing out in between filming duties ...  vibing on board a chartered boat off the coast of Favignana on Friday.

The 54-year-old was serving major silver-fox vibes with that epic beard, definitely channeling that relaxed movie star energy as he laughed, kicked back, and soaked up the sunshine.

And all that fitness grind? Totally paid off. Matt displayed serious athleticism, throwing down impressive backflips into the water like it was no biggie.

Of course, Matt’s been ditching the shirt a lot lately -- and it’s all for "The Odyssey," the star-packed epic he’s filming with Christopher Nolan. And honestly, no one's complaining -- he can rock the shirtless look as long as he wants!