BASE/B.A.S.E. Jumping is an activity where participants jump from fixed objects and use a parachute to break their fall. "BASE" is an acronym that stands for four categories of fixed objects from which one can jump: buildings, antennas, spans (bridges), and earth (cliffs).
In recent years advanced BASE jumpers have taken to wearing varying sizes of wingsuit to extend their flight time or extend flight their range. A smaller suit will generally be more manoeuverable but will produce less lift, and vice versa for larger suits.
BASE jumping is the most dangerous activity in the world, and with varying reports claiming it to be between to be 5 to 43 times more dangerous than parachuting from a plane. It is generally accepted that using a wingsuit whilst BASE jumping poses added dangers.
For those at the cutting edge of the sport, wingsuits are being used to fly close to the ground and fixed objects.