Umibozu

Umibozu are a race of giants living underwater. So far, the only known Umibozu is Wadatsumi.

Appearance
Umibozu are a very large species, towering over regular giants and almost the same size as the Kraken. The only known Umibozu, Wadatsumi, has a human-like appearance with a more ovular face and a hairy body.

Biology
As a subspecies of giants, the Umibozu can live up to three times longer than humans.

Like fishmen, they can breath underwater, and the immense water pressure of 7000 meters below surface seems to have no effect against them.

Overall Strength
They are an incredibly powerful race due to their enormous size. Wadatsumi can beat a huge fish, several times bigger than Thousand Sunny, with one punch. However, he was easily defeated by the Kraken Surume.

Trivia

 * Umibōzu (海坊主) is a spirit in Japanese folklore living in the ocean.