It's important to know that ordinary people would be exhausted after swimming about a hundred meters in the ocean. But Wang Ye swam several kilometers in succession without ever feeling tired, and he didn't even surface.
Because the gill slits on his neck allow him to breathe freely underwater, eliminating the risk of life-threatening oxygen deprivation. However, even without the gill slits providing oxygen, Wang Ye's current lung capacity would allow him to comfortably hold his breath and engage in normal activities all day.
Ever since completing the challenge of the Life of Water, Wang Ye hasn't trained his swimming. Even now, his Swimming Skill remains at lv4. But as his physique has strengthened, his swimming speed has long surpassed the human pinnacle, though his technique remains quite crude, at most reaching the level of a First-level Athlete. Any National Elite Level Swimmer could easily point out the flaws in his movements.
