California's Great America Home Six Flags California's Great America 1976 Marriott's Great America Resort Opened March 20, 1976 1976 Marriott's Great America Opened March 20, 1976 Theme Park 1985 Renamed to Great America Renamed June 1985 2004 Crocodile Dundee's Boomerang Bay Opened 2004 Water Park 2008 Renamed to California's Great America Renamed 2008