Cetus

Cetus, a character in the Endless Summer series, is a sea monster and the Sea Guardian of La Huerta. 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).

You are shown to be frustrated that Cetus seemingly can't die and always shows up unexpected. In Book 3, Chapter 4 you yell "Damn you, Cetus! Why can't you just leave us alone?"

At the end of Book 3, Chapter 7, you vow to hunt down Cetus and kill it once and for all.

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.