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 the same size as the head of a Kraken. The only known Umibozu, Wadatsumi, has a human-like appearance with a more ovular face and a hairy body.

Biology
Like fishmen, they can breath underwater, and the immense water pressure from 7000 meters under water seems to have no effect on 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.