Six Flags Great Adventure (Six Flags Entertainment, Inc.) is a well-known North American theme park chain founded in 1961 and headquartered in Grand Prairie, Texas, a publicly traded company (( NYSE: SIX). NYSE: SIX). Six Flags owns a number of theme parks and water parks in the United States, Canada and Mexico. Six Flags' official website provides information on opening hours and notes, as well as online ticketing.