"Yes, crevasses are cracks in the surface of a glacier, and in many cases they can be very dangerous. Usually they're created when a glacier is flowing downwards too fast for it to handle, or when it comes in contact with uneven terrain like a steep ledge or a sharp corner. Some crevasses are only a few centimetres deep, while others are so deep they penetrate the entire glacier! They're very easy to fall into, especially when they're concealed by a thin layer of snow, called a snow bridge. One step and you could fall right in! Better be careful."