Poseidon's Cabin

Poseidon's cabin (#3) is low, long and solid, with all the windows facing the sea. The outer walls are rough gray stone with pieces of seashell and coral and look like the bottom of the ocean floor. On the inside it has six empty bunk beds and the walls glow like abalone.

Later in the series, Poseidon adds a fountain for his sons (Tyson and Percy Jackson). It is made out of gray sea rock, has a fish that sprouts the water from its mouth, and has coral to decorate it. The bottom is filled with gold drachma for Iris messages, although it is unknown that if the coins will ever run out. Tyson later adds a few bronze Hippocampi on the ceiling as decorations. He also added unknown underwater plants and corals, sitting in the window sill, "more beautiful than the Demeter kids could whip up," Percy commented.

Known occupants

 * Percy Jackson (Counselor)
 * Tyson (when he visits)

Abilities
Main Article: Hydrokinesis

Cabin members may have some or all of the following:
 * Breathe underwater.
 * Children of Poseidon are some of the most powerful demigods alive since Poseidon is one of the Big Three Olympian gods.
 * Hydrokinesis
 * Telepathic connection to equestrian animals (horses, pegasi, hippocampi, etc.)
 * No harm when falling into water, even from great heights
 * Can withstand immense water pressure
 * Ability to stay or become dry in water (unless they choose to be wet)
 * Higher resistance to fire or burns
 * Can make water shoot out from petrified seashells
 * Control ships
 * Ability to determine exact nautical coordinates
 * Create air bubbles underwater.
 * Can make water into a solid path.
 * Telepathic communication underwater
 * Can harden water to form a physical barrier
 * Differentiate between salt water and fresh water.
 * Create earthquakes
 * Create hurricanes
 * Building skills (if they are a cyclops or part cyclops)
 * Some children of Poseidon may be able to walk on water as Orion could in the Greek Myths.

Legacy Powers

 * Some legacies of Poseidon can shapeshift into animals, but only those related to Periclymenus. No Greek demigods have been shown to have this ability, but Frank Zhang (a Roman demigod) has this ability.

Magic Items

 * Percy has a magical celestial bronze sword called Anaklusmos, or Riptide.
 * Percy has a magic wrist watch that transforms into a shield. It was given to him by Tyson in the disguise of a watch that Tyson didn't finish in time for the Quest for the Golden Fleece in The Sea of Monsters (lost in the first fight against Kämpe on Alcatraz Island on Alcatraz off San Francisco Bay off San Francisco, California).
 * Percy has a Minotaur's Horn he used to defeat with (Percy ripped off the horn while fighting the Minotaur in the book, and ripped it out of a tree trunk in the film) in front of Half-Blood Hill. The only entrance to Camp Half-Blood in The Lightning Thief book and film is by passing the small hill.
 * A Saltwater Fountain was provided by Poseidon for his children in The Titan's Curse, until Percy destroyed it in The Battle of the Labyrinth being scared of what he was hearing and seeing (about Nico).

The Lightning Thief (film)
Although not said to be the cabin, Percy stays in an open cabin by the beach built by his father, Poseidon. Chiron stated that Poseidon built it just for Percy, although he might have just meant all of his children, though he had no other demigod children. In the cabin, there was a life sized trident, and many other helpful objects that Percy could use. The cabin gave an excellent view of the ocean.

Trivia

 * Poseidon's cabin is tied with Zeus' cabin for having the third least amount of possible inhabitants, the first being Hera's cabin with no inhabitants.