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San Clemente Island


San Clemente Island is the southernmost of all eight of the Channel Islands and is located 113 nautical miles (nm) from Santa Barbara. It is 21 nm long and is 4-1/2 nm across at its widest point, with a total area of 57 square miles. The U.S. Navy acquired the island in 1934 and it has been owned and operated by various naval commands. San Clemente is also home to an auxiliary naval airfield, United States Navy SEALs training facilities, and the southern end of the island is the Navy’s only remaining ship-to-shore live firing range.

San Clemente Island is made of up of volcanic materials dating back to 5 million years ago. The terrain varies between exposed marine terraces and steep canyons dotted sparsely with freshwater springs. The island can be described as being on a ‘tilt;’ the north side rises dramatically out of the ocean (the highest point, Mt. Thirst, is 1,965 ft), while the south side has a much gentler slope to its rocky shores. With a frost-free, semi-arid climate, the island typically gets less than 6 inches of rain in a year.


Diving conditions at San Clemente Island are known for the clearest, warmest waters of all eight Channel Islands. Located in the southernmost region of California this island receives the warmest waters from the tropical currents from the south. Giant kelp beds, schools of fish, coral banks, and shear walls make this a diver’s paradise. Waters in the summer can reach over 70 degrees Fahrenheit and photographers flock to this island for some of the best wide-angle photography available in California.

Most of the prime scuba diving is located at each end of the island. The east end of the island is more protected and offers pinnacles, shear walls, and protected shallow kelp covered coves. San Clemente’s west end is more exposed to the westerly winds and swells but has some of the more prolific areas found off California. Nine Fathom Reef (it rises to 6 ½ fathoms) is a rocky structure with shear walls covered in purple hydrocoral. This is an open ocean diving location and is swept by currents and swells so diving this area can be tricky. Once dove, it is never forgotten.


Because of the military presence at the island, kayaking can be enjoyed near the boat only. As any on any of the Channel Islands, lush kelp beds, volcanic rock formations, and sea lions make kayaking well worth the effort. Generally, kayaking is done during one of Channel Islands Expeditions regularly scheduled liveaboard dive trips.


No island hiking available as landing is prohibited.


Human History

San Clemente Island is one of the best documented archeological settings in California. Archeologists have found traces of human occupation on the San Clemente Island dating back 10,000 years, a remarkable figure for an island 55 nautical miles out to sea, but consistent with results on other Channel Islands. The native inhabitants here called the island ‘Kinipar,’ and bore many cultural similarities to the nearby Nicholenos on San Nicolas Island. Travel between the islands was facilitated by the ‘ti’at,’ a plank canoe that enabled the islanders to cross wide channels and open ocean. Inhabitants here left trade materials from the northern islands and from the mainland, including Coso obsidian from the Mohave high desert. It has not been established what tribe the recent inhabitants belonged to, although the Tongva, from Santa Catalina Island and the Los Angeles Basin, are the most likely candidates. The Chumash who occupied the northern Channel Islands may have influenced the inhabitants.

The island was named by the mapping expedition Spanish explorer Sebastian Vizcaino, who spotted it on November 23, 1602; known as Saint Clement’s feast day in the Catholic tradition. The first actual visit happened much later in 1769, when the San Antonio of the Portola expedition anchored in Pyramid Cove on the south end of the island. Natives rowed out in ti’ats and exchanged gifts with the expedition, including two otter-fur robes. It was later used by ranchers, fishermen, and smugglers during the 19th century and into the 20th century. In the 1920s and 1930s the factory ships Lansing and California anchored off San Clemente Island, processing blue and fin whales, among other species, caught by their own fleets of steam-driven whale catchers.

Natural History

In recent years effort has been made by several conservation organizations, including Channel Islands Restoration, to remove invasive species from San Clemente Island and promote the re-emergence of native and endemic flora and fauna. The removal of invasive ice plant has encouraged native plants, like the boxthorn (Lycium spp.) to flourish. This is especially important as many endemic species of birds and reptiles use this native plant as cover and nesting habitat.

The San Clemente Island Loggerhead Shrike (Lanius ludovicianus mearnsi) is an endangered species that the Navy is taking steps to protect. The Island fox (Urocyon littoralis) and San Clemente Island brodiaea (Brodiaea kinkiensis) are notable examples of endemic species on the island. Feral goats roamed the island for centuries, reaching a population of 11,000 in 1972 when their effect on indigenous species was realized. By 1980 the population had been reduced to 4,000 and a plan for shooting remaining goats was blocked in court by the Fund for Animals, so the goats were removed with nets and helicopters.