UMIBŌZU

Giant monster living in the ocean

Umibōzu (海坊主, "sea priest") is a giant humanoid black figure of a yōkai from Japanese folklore. Normally, umibōzu appears to sailors on calm seas which quickly turn tumultuous. It either breaks the ship on emergence or demands a bucket or barrel from the sailors and proceeds to drown them. The only safe way to escape an umibōzu is to give it a bottomless barrel and sail away while it is confused.

Text from en.wikipedia.org/wiki/Umibōzu

Utagawa Kuniyoshi, Umibōzu, 1845

Implicit reference
Explicit reference