Kiteboarding, also known to kiteboarder's as kitesurfing. It involves using a large kite that gives traction and lift, (and these days has 4 or five lines) using a wake type or surf type board with bindings (foot straps) to hold your feet in place. By using the kite's power and holding down the power of the kite using your feet, you can pull off massive airs 30 foot+. The kites normally have a way of storing air inside them incase the kite were to land on the water it wouldn't sink.The boards usually range from 100cm in length to over 180cm.
I'm going kiteboarding tomorrow in the lake.