The fastest fish in the ocean is the sailfish. By flattening its large sail-like dorsal fin to its back, and thus streamlining its body, it is capable of swimming at speeds of 100 km/h (60 mph) over 90 m (300 ft) - faster than a sprinting cheetah. By comparison, the fastest human swimmer can manage only about 8 km/h (5 mph).
The fastest swimming mammal is the common dolphin, which can reach speeds of 55 km/h (35 mph). This great speed is achieved with minimal muscular effort and can, in part, be attributed to the dolphin's silky smooth skin, which is lubricated with oil. (Artificial skin similar to that of the dolphin has been produced for torpedoes to reduce turbulence and achieve greater speed.)
As with swimming, the diving abilities of animals put humans to shame. The deepest possible human breath-held dive, without artificial aids, is about 100 m (330 ft). Emperor penguins can reach depths of more than 260 m (850 ft) and remain underwater for 18 minutes.
But even this remarkable feat pales into insignificance when set beside the achievements of the world's champion diver, the sperm whale.
A signalling device was attached to a sperm whale and recorded a dive of 2250 m (7380 ft), a depth equivalent to five times the height of the Empire State Building and half the height of Mont Blanc (the highest mountain in the Alps and in Western Europe). By contrast, humans have only reached depths of 686 m (2263 ft), using gas cylinders and pressurised suits.