Santa Monica is a beachfront city in Southern California.
Percy Jackson and the Olympians
The Lightning Thief
After escaping the Underworld, Percy Jackson, Annabeth Chase, and Grover Underwood end up in the Pacific Ocean just outside the city. They are brought to shore by the Cost Guard and the son of Poseidon later fights Ares on a beach within the city limits.
The Trials of Apollo
The Burning Maze
After saving Herophile from Caligula, Apollo and Meg McCaffrey go to an airfield within the city to fly with the body of Jason Grace to San Francisco.