This was merely a feat of staying in the water.

In London in 1881, Beckwith, swimming ten hours a day over a 32-lap course for six days, traversed 94 miles.
Since the time of Captain Webb, who was the pioneer of modern long-distance swimming, many men have attempted and some have duplicated his feats; but these foolhardy performances have in late years been diminishing, and many of the older feats are forbidden by law.
Jumpers and acrobatic tumblers have been popular from the earliest time.

By the aid of springing boards and weights in their hands, the old jumpers covered great distances.

Phayllus of Croton is accredited with jumping the incredible distance of 55 feet, and we have the authority of Eustache and Tzetzes that this jump is genuine.

In the writings of many Greek and Roman historians are chronicled jumps of about 50 feet by the athletes; if they are true, the modern jumpers have greatly degenerated.