Watch the moment a glacier collapses!

Great big sheets of ice regularly fall off this glacier in South America! No wonder people go to watch!

This glacier is in Argentina and it's what happens when water pressure builds up under the ice making it weak.

It's part of a cycle and means tourists can see the spectacle of huge chunks of ice falling off the glacier every few years.

The Perito Moreno glacier in Argentina's Patagonia region is one of very few glaciers around the world that grows rather than shrinks but scientists say that overall the amount of glacial ice in the Patagonia region is decreasing.