San Nicolas Island is one of the Channel Islands located off the coast of California. It is the second-largest island in the Channel Islands National Park and covers about 14 square miles. The island is known for its rugged terrain, diverse wildlife, and unique ecosystems, making it a significant area for conservation efforts. The island is primarily used by the U.S. Navy for testing and training purposes. Access to San Nicolas Island is limited, and it is not open to the general public. The island is home to various species, including the endangered California sea lion and several bird species, contributing to its ecological importance.