An icebreaker is a ship with a heavy bow and armored sides, designed with powerful engines which enable it to make a passage through ice. For breaking thick ice, the bow is so designed that the forward motion of the ship drives it up onto the ice, and the weight of the ship breaks it. Propellers fore and aft allow great maneuverability. Icebreakers are used regularly to clear channels in the Great Lakes and in the Baltic Sea, and they have also been used in the Arctic and Antarctic explorations. The Soviet icebreaker Lenin, launched in 1959, was the first nuclear-powered, non-naval vessel.