As of 2015, the official record for world's fastest boat belongs to the Spirit of Australia, which travelled 317.58 miles per hour on Oct. 8, 1978. It is estimated that the same boat reached an unofficial speed of 344.86 miles per hour on Nov. 20, 1977, reports Guinness World records.
The Spirit of Australia is an unlimited-class jet-powered hydroplane. Separate records are kept for other types of boats. For example, the world's fastest propeller driven boat, Problem Child, reached a speed of 260.98 miles per hour on Nov. 22, 2009, according to Guinness World Records. The Vestas Sailrocket 2 became the fastest sailboat in the world when it traveled over 75 miles per hour in November 2012, claims Sailing World.