The Grand Canyon is a steep-sided canyon carved by the Colorado River in Arizona, United States, and is one of the many natural wonders of the U.S. It is eighteen miles (29 km) wide in some places, 220 miles (350 km) long, and plunges to depths of 5,970 - 6,000 ft (1,800 - 1,820 m). It is mostly contained within the Grand Canyon National Park, one of the first national parks in the United States. It has a viewing platform shaped as a U.
Jason Grace, Piper McLean, and Leo Valdez visit the Grand Canyon on a Wilderness School field trip. While doing a worksheet on the observation platform, the three demigods and their protector Gleeson Hedge are attacked by Dylan, a ventus in disguise, by the sorceress Medea's orders. Leo is thrown off the bridge by Dylan and saved by Coach Hedge, who, being a satyr, is able to climb down the canyon wall thanks to his goat hooves. Meanwhile, Jason distracts the venti with his sword Ivlivs. Piper is also thrown off the bridge and into the canyon, but Jason saves her by jumping over the sky-walk to save her, using his powers over air to control the currents. After Dylan escapes with Hedge, Annabeth Chase and Butch arrive and take them to Camp Half-Blood.
|Magical Locations:||Aeolia | Camp Half-Blood (Grove of Dodona) | Camp Jupiter | Cave of Trophonius | 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 | Detroit | Gila Claw | Indianapolis | Jamestown | Long Island | New Mexico | New York City (Manhattan) | Quebec | San Francisco | Dalmatia (Split) | Vancouver | Venice | Westport|
|Other Locations:||Apennine Mountains | Aunty Em's Gnome Emporium | Carlsbad Caverns | 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 | U.S.A. | Waterland|