Cetus

Cetus, a character in the Endless Summer series, is a sea monster. It first appears in Book 1, Chapter 11.

Appearance
Cetus is shown to be a gigantic reptilian creature covered in scales. It has horns where its eyes should be.

Your Character
It immediately has a hostile encounter with Jake, Sean, and possibly your character if he/she joins them on the speedboat. A premium option (if you choose to join Jake and Sean in the first place) gives you the opportunity to fight it with a Semtex found in the speedboat and a flare gun found in the marina (provided the latter isn't used before).

Trivia

 * Michelle's Catalyst Idol shows her getting killed by Cetus. It was later revealed that this happened in one of the past timelines. In a different timeline, both she and Raj were killed during Cetus's attack on the Vaanti village.
 * Jake's nickname for Cetus is Freakachu, a reference to the Pokémon character Pikachu, because of its electric attacks.
 * If you didn't fight him in Book 1, it will have its scarred appearance in Book 3.
 * In the bonus scene in Act 7, it is shown that swallowing the Island's Heart has evolved it into a hydra, with each head having a different color: scarlet, blue, and green.