Cabin 3: Poseidon

Poseidon's Cabin is a long, low building with windows facing the ocean, and looking like it's made of rough sea stone, with pieces of coral at the end of the cabin and a seashell and a trident over the door. Percy described its smell to be same as the cabin at Montauk where his mother and father met. Percy also states that there is always a sea breeze blowing through it.
Inside: walls made of abalone with rows of neat bunks, and a salt water fountain given to Percy (until he cut it in half). There is also a sort of mobile of hippocampi or "fish-ponies" as Tyson calls them.