Chris Hemsworth Loves His Wife Elsa Pataky's Butt in a Bikini

Chris Hemsworth got ALL UP in his wife's business when he got a handful of her ass during a family day at the beach.

No doubt about it ... Chris was a huge fan of Elsa Pataky's choice in swimwear -- a very small black bikini -- during their family's Sunday funday. The stupidly hot couple's been married for more than 7 years now, so they obviously made it through that 7-year-itch thing, just fine.

The Hemsworths were hosting Matt Damon and his family in their hometown of Byron Bay, Australia this weekend. They all went to a music festival together, but we're guessing Chris and Elsa had a much better time at the beach.