Base jumping participants leap from a stationary object at a high altitude while wearing a parachute to break their fall. The acronym "BASE" stands for "Building, Antenna, Span and Earth," which describes the four categories of objects from which the jumpers launch themselves.
Bungee jumpers also leap from lofty perches, but instead of using a parachute, the jumpers are attached to a long elastic cord that pulls them up when it snaps back at the end of a fall. Jumpers typically leap from a tall building or a bridge over a body of water.
Land luge is akin to the luge event in the Winter Olympic Games, except that lugers lie on their backs on boards with wheels and travel on a land track instead of ice. Lugers can attain speeds of 80 miles per hour and navigate the course's turns by leaning their bodies to either side. Lugers slow down or stop by applying foot brakes.
Whitewater rafters pilot canoes, kayaks and rafts on rivers that feature high-speed rapids. They might travel alone or in a vessel with several others. Vigorous paddling is necessary to keep the craft upright and to avoid obstacles such as large rocks.
Windsurfing combines elements of sailing and surfboarding. Windsurfers attempt to navigate ocean waves on special surfboards with attached sails. Advanced windsurfers often perform acrobatic maneuvers like spins, jumps and loops.
Mountain bikers ride specially-built bicycles featuring wide, thick tires and sturdy frames. The bikers often traverse mountain trails filled with hills, rocks and sharp bends while moving at a high rate of speed.
As the name implies, rock climbers attempt to ascend the sides of hills or mountains by using their feet and hands for propulsion and support. Rock climbing can take place indoors at facilities that feature specially-constructed rock walls.