Whale

Whales are gigantic marine mammals live completely in the waters. Dolphins and porpoises are relative to whales (biologically, these are members of whales).

They are the largest organisms in the real world, and are possibly the only of normal creatures being comparable in size to sea monsters, sea serpents and their relatives. It is unclear how large whales can grow up in the world of the Pirates of the Caribbean and thus whether or not being comparable or exceed the size of the Kraken.

Legendary White Whale appears in the history or lore where this animal devoured Viking King in northern sea.

Exploitations
"Smell that? Whale oil. Stuff burns like a miracle from God." "Can you make it work?" "Made by the English. Let's not get our hopes up."

- Salaman and Blackbeard

Whales were heavily hunted for centuries mostly for oils and baleens, resulting in one of the pioneering reasons for men to sail and explore the oceans. Men ventured across the vast waters, and many ports such as Boston were opened for this purpose. these were used for various gears and lights. The lighthouse of notorious Whitecap Bay also used whale oils for lightening.

Trivia

 * The whale skeleton to appear in the Pirates of the Caribbean: Dead Men Tell No Tales is clearly of a baleen whale based on the skull, however this could be a unique whale species because the skull shows characteristics of the Right Whale (one of pioneering targeted species by early whaling), but the body bones are much larger than the real right whales.
 * Right whales are some of the most rare and endangered whale species in the world.
 * It is currently unclear whether or not right whales historically migrated into the Caribbean Sea in real world while it had been thought until recently that right whales won't migrate up to Gold Coast (the filming location), but small numbers of right whales are now appearing thanks to recovery of the species.