There exists a dubious record of a small blue shark about 2 feet (0.6 metres) in length which was found to swim steadily against a current at 17.7 miles (28.5 kilometres) per hour and was reported to achieve 43 miles (69 kilometres) per hour in short bursts. According to the same study, male great white sharks take 26 years to reach sexual maturity, while the females take 33 years to be ready to produce offspring. Great white sharks can reach swimming speeds as fast as 25 miles per hour. In a 25 yard pool, 1.2 miles is around 2000 yards, or 80 lengths. Most sharks have long gestation (pregnancy) periods, some species like basking sharks and frilled sharks have a.