Six Flags Discovery Kingdom (formerly known as Six Flags Marine World, Marine World, The New Marine World Theme Park, and Marine World Africa USA) is a 135-acre (55 ha) animal theme park located in Vallejo, California, roughly halfway between San Francisco and Sacramento on Interstate 80. The park includes a variety of roller coasters and other amusement rides, along with a collection of animal exhibits and shows. Discovery Kingdom has been part of the Six Flags chain of amusement parks since 1999.