Isla San José is the second largest island in the Pearl Islands, and has an area of 44 km². At the 2000 census, it had a population of 10. The privately owned island has an area of about 17 square miles. Thousands of wild pigs and deer populate Isla San Jose, which has a rugged, rocky shoreline and over 50 beaches.
A unit of U.S. soldiers tested chemical arms from 1945 to 1947 on the then deserted island, leaving behind at least eight unexploded 500 and 1,000-pound bombs. A U.S. military text states that the larger bombs contained phosgene and cyanogen chloride, and smaller ones mustard gas. Other reports state that the soldiers also tested VX nerve gas and sarin. Unexploded ordnance on the islands is estimated in thousands of units of highly dangerous chemical mines. An unknown but large amount of munitions was also dropped into the sea around the island.
The island is served by San José Airport.