Rafting and white water rafting are recreational outdoor activities which use an inflatable raft to navigate a river or other body of water. This is often done on whitewater or different degrees of rough water, and generally represents a new and challenging environment for participants. Dealing with risk and the need for teamwork is often a part of the experience. The development of this activity as a leisure sport has become popular since the mid-1970s, evolving from individuals paddling 10 feet (3.0 m) rafts with double-bladed paddles to multi-person rafts propelled by single-bladed paddles and steered by a tour guide at the stern. It is considered an extreme sport, and can be fatal. The International Rafting Federation, often referred to as the IRF, is the worldwide body which oversees all aspects of the sport.