The Channel Islands () are an eight-island archipelago located within the Southern California Bight in the Pacific Ocean, off the coast of California. The four Northern Channel Islands are part of the Transverse Ranges geologic province, and the four Southern Channel Islands are part of the Peninsular Ranges province. Five of the islands are within the Channel Islands National Park, and the waters surrounding these islands make up Channel Islands National Marine Sanctuary. The Nature Conservancy was instrumental in establishing the Channel Islands National Marine Sanctuary. The islands were inhabited as early as 13,000 years ago, the earliest paleontological evidence of humans in North America. They are the easternmost islands in the Pacific Island group. The Chumash and Tongva Native Americans who lived later on the islands may be the descendants of the original inhabitants, but they were then displaced by Spaniards who used the islands for fishing and agriculture. The U.S. military uses the islands as training grounds, weapons test sites, and as a strategic defensive location. The Channel Islands and the surrounding waters house a diverse ecosystem with many endemic species and subspecies. The islands harbor 150 unique species of plant. Characteristics The eight islands are split among the jurisdictions of three California counties: Santa Barbara County (four), Ventura County (two), and Los Angeles County (two). The islands are divided into two groups; the northern Channel Islands and the southern Channel Islands. The four northern Islands used to be a single landmass known as Santa Rosae. The archipelago extends for between San Miguel Island in the north and San Clemente Island in the south. Together, the islands’ land area totals , or about . Five of the islands (San Miguel, Santa Rosa, Santa Cruz, Anacapa, and Santa Barbara) were made into the Channel Islands National Park in 1980. The Channel Islands National Marine Sanctuary encompasses the waters off these islands. Santa Catalina Island is the only one of the eight islands with a significant permanent civilian settlement—the resort city of Avalon, California, and the unincorporated town of Two Harbors. University of Southern California also houses its USC Wrigley Institute for Environmental Studies marine lab in Two Harbors. The Channel Islands National Park mainland visitor center in Ventura Harbor received 342,000 visitors in 2014. The islands attract around 70,000 tourists a year, mostly during the summer. Visitors can travel to the islands via public boat or airplane transportation. Camping