26 April 2017 Last updated at 11:37 BST
Each spring, millions of red, yellow and black land crabs march for days to get from the forests on the Caribbean island down to the sea.
They get everywhere!
They climb up walls, sneak into houses and shops and they cover the roads, making it hard for cars to drive around them.
But why are so many crabs heading for the sea?
Well, the adult crabs lay loads of eggs in the waves before the babies hatch at sea and then return to their parents in the forest.
Not so creepy after all!
Check out our video of the crab invasion that has taken over Cuba!!