Spirit of Australia – 318 mphThe Spirit of Australia is the fastest boat to ever touch water. Designed and built in a backyard by Australian powerboat racer Ken Warby, this jet-powered hydroplane clocked 317.6 mph in 1978 on Blowering Dam in New South Wales. It hasn't been beaten since.Powered by a Westinghouse J34 turbojet engine stripped from a fighter plane, the Spirit of Australia didn't use propellers. It used jet propulsion to shoot a stream of water backward and create enough thrust to accelerate incredibly fast over short distances. That let Warby hit the kind of speeds that would normally need a runway. The boat is incredibly light for its speed, built from marine wood and fiberglass.Despite multiple challengers over the years, the Spirit of Australia's record still stands. Warby's son even built a follow-up, Spirit of Australia II, in the hopes of breaking their own record, but the original remains untouched.Problem Child – 262 mphIn drag boat racing, Problem Child is king. Powered by an 8,000 horsepower nitro engine, this boat goes from zero to 262 mph in just 3.5 seconds.Built and raced by Eddie Knox and Larry Bless, Problem Child is a nitro drag boat that's won multiple world championships. It's responsible for the 15 fastest 1,000-foot elapsed times in drag boat history. This thing is built for pure, straight-line acceleration.What makes it even more wild is that the powerplant is similar to what you'd find in NHRA Top Fuel dragsters. Same size. Same setup. Just mounted to a hull skimming across water instead of tires gripping asphalt. Knox's team even partnered with Kalitta Motorsports for tech and parts crossover, helping the boat become the reigning champion of the Lucas Oil Drag Boat Series.Despite the boat crashing at 263 mph in 2013, it was rebuilt and raced again the very next day. That sums up the spirit of the crew behind it: fearless and focused.