If you're heading to the North Pole by sled, watch out you don't fall into a crevasse — a deep fissure or crack in the snow or ice. Similar to the term "crevice," though "crevice" usually refers to a fissure in a rock face. Neither one is a nice place to get stuck.
The word crevasse, as its spelling suggests, comes from an old French word, the verb crevare, meaning "to burst or break," and indicating how a crevasse was formed in the first place. The reason for the difference in the two terms, crevasse and crevice, was originally to indicate a difference in size: in general a crevasse is much larger than a crevice, which can often be extremely small.