Actor Chris Hemsworth was soaking up the last days of summer Down Under last week ... out surfing near his hometown of Byron Bay, Australia.

The Aussie clearly knows his way around the water, ripping waves on his shortboard, catching a few 4-footers on his twin-fin. Check out the vid ... He looked great laying rail on his cutbacks, even catching a little tube time.

Afterward, the Hollywood hunk shed his wetsuit top, looking shredded after he finished shredding, trotting up the sand in his little star-covered trunks.

The 'Thor' superstar seems to be enjoying a bit of leisure between projects, taking time to tap some tasty waves back home in the surf-obsessed nation.

Killer session, mate!