Mark Wahlberg's looking absolutely shredded these days ... so there's clearly no reason for him to ever put a shirt back on, right?
The 46-year-old actor was spotted with his model wife Rhea Durham Thursday on a beach in Barbados ... showing off all of his muscles and his washboard abs.
It's funny -- just a day earlier, Wahlberg popped in on one of our TMZ Tour buses and sent the group into a frenzy ... but just imagine the reaction if he was shirtless then too.