Amy Roloff knows how to do vacation the right way -- dance your ass off as much as possible ... and enter a cannonball contest.
The matriarch of "Little People, Big World" didn't let her stature stop her from grabbing the spotlight Wednesday on a cruise ship in the Caribbean. Amy was shaking her booty and having a blast before she took the plunge in the competition.
We're told the top finishers got prizes sent to their rooms, and based on the size of Amy's splash, it's no surprise she didn't win ... but she did come in third!
It's unclear what prize she got, but the reality show mom def won some respect for going for it.
Amy departed for the tropical getaway with her bf, real estate agent Chris Marek, a few days ago. As we reported ... Amy and her ex-husband, Matt, finalized their divorce about 2 years ago.