The Leviathan is a massive gem sea serpent that guards the Triton of Water.
Because of its massive size, it has extreme power behind the scales of the beast. It is also shown to have powerful jaws that can tear through rock. It also has an ability to fly with its wings and can fire scolding hot water at enemies.
Heart of Water: In the episode, it guards the triton from anyone retrieving it. It is shown to be quite defensive of the elemental weapon and is also shown to be extremely dangerous. It would have eaten Lapis if it wasn't for Steven with the triton.
The Rise of Onyx: It is shown that Lapis trained the leviathan and now is her pet and secret weapon in battle. She tries to fight with the leviathan against Onyx but he was too powerful for the leviathan to beat.
- The leviathan is based on the mythical sea monster.
- The leviathan becomes Lapis' pet.
- It is revealed to have wings in the episode, the Rise of Onyx.
- The leviathan's boiling water attack is a reference to the Scauldron in Dragons: Riders of Berk.