Kayaking is the use of a kayak for moving across water. Kayaking and canoeing are also known as paddling. Kayaking is distinguished from canoeing by the sitting position of the paddler and the number of blades on the paddle. A kayak is defined by the International Canoe Federation (the world sanctioning body) as a boat where the paddler faces forward, legs in front, using a double-bladed paddle. Most kayaks have closed decks, although 'sit-on-top' kayaks are growing in popularity, as are inflatable kayaks which come without decks but which have air chambers surrounding the boat.