Kayaks are small, narrow human-powered boats propelled by double-bladed paddles. They originated with Ainu and Eskimo hunters over 4,000 years ago and have since been used for transportation, fishing, racing, and recreation. There are various kayak types depending on their hull and use, including sit-on-top, fishing, sea, and expedition kayaks. Kayaking has grown as a competitive sport with rules for surfing and wildwater racing over different course lengths and timed runs. Kayaking tours are also organized in Abu Dhabi to discover the local aquatic landscape and encourage tourism.