Brooks Nader Gets Wet 'n Wild in Thong Bikini on Sisters Trip

Brooks Nader is giving fans a show once again ... this time rocking a thong bikini -- with no top to go with it -- during her ongoing vacation in Italy.

Check out the pics from her Wednesday Instagram Story post -- the Sports Illustrated Swimsuit Issue cover girl showed off her toned derrière as she balanced on a floating obstacle course off the coast of Sardinia ... wearing brown bottoms with nothing to cover her top half.

Brooks looks like she's having one wet 'n wild time on the European getaway ... which includes her sisters Mary Holland Nader, Grace Ann Nader and Sarah Jane Nader, plus some friends.

She shared another glimpse of their stunning vacation on Instagram Thursday as well -- which saw the gal pals getting glitzed and glammed in cowgirl-inspired getups.

The "Dancing with the Stars" alum showed off her figure in a semi-transparent blue corset dress from Italian fashion house Ermanno Scervino and paired it with a bedazzled cowgirl hat.

The picturesque trip comes as Brooks and her sisters promote their upcoming Freeform reality series "Love Thy Nader," which is due out August 26.