Some modern boats vary considerably from a traditional design but still claim the title "kayak", for instance in eliminating the cockpit by seating the paddler on top of the boat ("sit-on-top" kayaks); having inflated air chambers surrounding the boat; replacing the single hull by twin hulls, and replacing paddles with other human-powered propulsion methods, such as foot-powered rotational propellers and "flippers". Kayaks are also being sailed, as well as propelled by means of small electric motors, and even by outboard gas engines.
Kayaks (Inuktitut: qajaq (ᖃᔭᖅ Inuktitut pronunciation: ), Yup'ik: qayaq (from qai- "surface; top"), Aleut: Iqyax) were originally developed by the Inuit, Yup'ik, and Aleut. They used the boats to hunt on inland lakes, rivers and coastal waters of the Arctic Ocean, North Atlantic, Bering Sea and North Pacific oceans. These first kayaks were constructed from stitched seal or other animal skins stretched over a wood or whalebone-skeleton frame. (Western Alaskan Natives used wood whereas the eastern Inuit used whalebone due to the treeless landscape). Kayaks are believed to be at least 4,000 years old. The oldest existing kayaks are exhibited in the North America department of the State Museum of Ethnology in Munich, with the oldest dating from 1577.
Native people made many types of boat for different purposes. The baidarka, developed by indigenous cultures in Alaska, was also made in double or triple cockpit designs, for hunting and transporting passengers or goods. An umiak is a large open sea canoe, ranging from 17 to 30 feet (5.2 to 9.1 m), made with seal skins and wood. It is considered a kayak although it was originally paddled with single-bladed paddles, and typically had more than one paddler.
Native builders designed and built their boats based on their own experience and that of the generations before them, passed on through oral tradition. The word "kayak" means "man's boat" or "hunter's boat", and native kayaks were a personal craft, each built by the man who used it—with assistance from his wife, who sewed the skins—and closely fitting his size for maximum maneuverability. The paddler wore a tuilik, a garment that was stretched over the rim of the kayak coaming, and sealed with drawstrings at the coaming, wrists, and hood edges. This enabled the "eskimo roll" and rescue to become the preferred methods of recovery after capsizing, especially as few Inuit could swim; their waters are too cold for a swimmer to survive for long.