A kayak is a small human-powered boat. It typically has a covered deck, and a cockpit covered by a spraydeck also known as a skirt. The kayak was used by the native Ainu, Aleut and Eskimo hunters in sub-Arctic regions of northeastern Asia, North America and Greenland. It historically was, and often still is, propelled by a double-bladed paddle in the hands of a sitting paddler. Modern kayaks come in a wide variety of designs and materials for specialized purposes. In some parts of the world, such as the United Kingdom, kayaks are referred to as canoes and vice versa.

Traditional kayaks typically accommodate one, two or occasionally three paddlers who sit facing forward in one or more cockpits below the deck of the boat. If used, the spraydeck or similar waterproof garment attaches securely to the edges of the cockpit, preventing the entry of water from waves or spray, and making it possible, in some styles of boat, to roll the kayak upright again without it filling with water or ejecting the passenger.