The official world water speed record is 275.97 knots (511.11 km./h, or 317.58 mph) by Ken Warby in the unlimited-class jet-powered hydroplane Spirit of Australia on Blowering Dam Lake, New South Wales, Australia, on 8 October 1978. However, it is estimated that Warby reached an estimated 300 knots (555 km/h., or 344.86 mph) unofficially at the same location on 20 November 1977.