The ability to swim was common among the ancients. (Ezek. 47:5; Acts 27:42, 43) In an early Egyptian text, a father mentions that his children took swimming lessons, and Assyrian reliefs depict warriors as swimming, often with the aid of inflated skins.
Ability to swim was a must for fishermen. When using a dragnet, they, likely as in more recent times, would occasionally dive into the water and pull a portion of the weighted edge under the rest of the net to form a bottom. Although apparently a good swimmer (John 21:7, 8), the fisherman Peter began to sink and called for Jesus Christ to save him at the time Peter walked on the water. This was likely the result of the unusually rough water, coupled with Peter’s personal fear.—Matt. 14:27-31.
In a prophecy against Moab, Isaiah alluded to the actions of a swimmer, saying: “The hand of Jehovah will settle down on this mountain, and Moab must be trodden down in its place as when a straw heap is trodden down in a manure place. And he must slap out [literally, stretch(es) out] his hands in the midst of it as when a swimmer slaps them out to swim, and he must abase its haughtiness with the tricky movements of his hands.” (Isa. 25:10, 11) This rendering, as does the Septuagint Version, suggests that Jehovah stretches out his hands against Moab to deliver destructive blows. Another reading, however, makes Moab the one doing the swimming. An American Translation, for example, states: “The hand of the LORD will rest on this mountain, but Moab will be trampled down where he stands, as straw is trampled down in the water of a dung-pit; and though he spread out his hands in the midst of it, as a swimmer spreads out his hands to swim, his pride will be laid low despite all the tricks of his hands.”