A sea serpent is a type of a sea monster either wholly or partly serpentine. They resemble to Drakons and Dragons, but do not spit poison, live in water, and hold other minor differences. Poseidon has the ability to control the sea serpents/monsters.
A sea serpent with a head like a crocodile was used by Deimos to scare people and attack his demigod sister, Clarisse La Rue, and Percy. It is said by Percy that they are "big babies when it comes to getting hurt".
Oceanus used a sea serpent as a sword when he attacked Poseidon's palace. One sea monster tried to attack the palace but Poseidon blasted it with his trident. After the Second Olympian War, while fishing, Poseidon talks to Percy and catches a huge green sea monster but cuts it loose saying it was "not eating size".
It is mentioned that Percy strangled a sea monster in the Carquinez Strait.
One of Keto's children, a skolopendra attacks the Argo II and damages the ship. It tries to capture Frank Zhang, Leo Valdez, and Hazel Levesque but Leo and Hazel throw Greek fire into its mouth and it drops them. They are then rescued by Ichthyocentaurs, who remark that Keto must really hate the demigods since she sent one of her biggest monsters after them.
Notable Sea Monsters
- Sea Monsters were often used on maps to mark areas of the sea that had not yet been explored.
|Species:||Centaur | Cyclopes | Dragon | Drakon | Empousa | Fire-Breathing Horse | Giants | Gorgon | Harpy | Hyperborean Giant | Ichthyocentaur ||
|Friendly Monsters:||Argus | Blackjack | Briares | Chiron | Don | Ella | Festus | Gleeson Hedge | Gray |Grover Underwood | Hippocampus | Mellie | Mrs. O'Leary | Ophiotaurus | Peleus | Scipio | Tyson | Tempest|
|Enemy Monsters:||Agrius and Oreius | Arachne | Basilisk | Charybdis and Scylla | Chimera | Chrysaor | Clazmonian Sow | Colchis Bull | Echidna | Euryale | Geryon | Joe Bob | Kampê | | Nanette | Manticore | Medusa | Minotaur | Nemean Lion | Polyphemus | Sphinx | Stheno | Typhon | Scythian Dracanae|
|Neutral Monsters:||Carnivorous Sheep | Cerberus | Erymanthian Boar | Gray Sisters | Gorgons | Furies | Flesh-Eating Horse | Gryphon | Siren|