@numbersdictionary: 68 (mph) The speed of the sailfish, the fastest animal in the world. Known as the fastest swimmer in the seas, the sailfish can reach speeds of exactly 68 miles per hour. These impressive creatures, which live in the Atlantic and Pacific oceans, have an average lifespan of 13 years. Although their length is usually around 9 feet, some can reach up to 12 feet. They can weigh up to 220 pounds.