When it comes to the fastest animals on water, fish take the lead. Sailfish are the fastest animals in the water at 70 miles per hour or 113 km per hour – the same speed in the water as cheetahs attain on land. Mako sharks can reach 60 miles per hour or 97 km per hour, and marlins, 50 miles per hour or 80 km per hour. The fastest mammal in the water is the killer whale, which can swim at up to 48 miles per hour or 77 km per hour.
But neither insects, reptiles, mammals, nor terrestrial bird speeds come anywhere close to birds in flight. Birds are not only the fastest animals in the air: they are the fastest animals on earth. Swifts can fly at 106 miles per hour or171 km per hour. Peregrine falcons fly at 90 miles per hour or 171 km per hour and dive at 200 miles per hour or 322 km per hour. In other words, the short answer to the question is: peregrine falcons are the world’s fastest animals.