Percy Jackson, Nico di Angelo, and Mrs. O'Leary shadow travel there to find out about Luke Castellan's childhood and the requirements of bathing in the River Styx. They meet Hestia here just before they leave for the Underworld.
|Magical Locations:||Aeolia | Camp Half-Blood | Camp Jupiter | C.C.'s Spa and Resort | Daedalus' Workshop | Lotus Hotel and Casino | Mount Othrys | Ogygia | Olympus | Pan's Cave | Sea of Monsters | The Labyrinth | Tartarus | Underworld | Waystation|
|Cities, States, and Towns:||Alaska | Bar Harbor | Bologna | Chicago | Dalmatia | Detroit | Gila Claw | Indianapolis | Jamestown | Long Island | Manhattan | New York City | Quebec | San Francisco | Split | Vancouver | Venice | Westport|
|Other Locations:||Apennine Mountains | Aunty Em's Gnome Emporium | Crusty's Water Bed Palace | Empire State Building | Gateway Arch | Grand Canyon | Greece | Hoover Dam | Italy | Junkyard of the Gods | Mount Diablo | Mount Etna | Mount Saint Helens | Mount Tamalpais | Pikes Peak | Polyphemus' Island | ROFL | Rome | Triple G Ranch | Waterland|