A kayak is a small, relatively narrow, human-powered boat primarily designed to be manually propelled by means of a double blade paddle. The traditional kayak has a covered deck and one or more cockpits, each seating one paddler. Their cockpit is sometimes covered by a spraydeck (or "skirt") that prevents the entry of water from waves or spray and makes it possible for highly skilled and specially trained kayakers, to roll the kayak: that is, to capsize and right it without it filling with water or ejecting the paddler. In modern kayaks, such recovery methods have been replaced by a preventive approach based on increasing the kayak's stability, and by that reducing the likelihood of its capsize. Many modern kayaks have modified the traditional design in various ways, such as: 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 ("W" kayak), 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, when possible.
In some parts of the world, such as the United Kingdom, kayaks may be considered a subtype of canoes.
The kayak was first made and used by the native Ainu, Aleut and Eskimo hunters in sub-Arctic regions of northeastern Asia, North America andGreenland.
Kayaks (Inuktitut: qajaq, Inuktitut syllabics: ᖃᔭᖅ Aleut: Iqyax) were originally developed by the Eskimos, who used the boats to hunt on inland lakes, rivers and coastal waters of the Arctic Ocean, North Atlantic,Bering Sea and North Pacificoceans. These first kayaks were constructed from stitched seal or other animal skins stretched over a wood or whalebone-skeleton frame. (Western Inuit 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