Franky Zapata's invention, the Flyboard, is part jet pack and part jet ski. Riders can climb as high as ten meters above the water, then dive under it. It's controlled with streams of water from the hands and feet. But that fun will cost you $12,000 per unit.
Link (warning: auto-sound) -via Sarah Hoyt
http://www.naturalbraid.com/index.php?route=product/product&product_id=156