Crab Island is a roughly 40-acre (160,000 m²) limestone island situated just outside Plattsburgh Bay in the town of Plattsburgh in Clinton County in upstate New York's Lake Champlain. During the War of 1812, the island was utilized as a military field hospital for convalescent soldiers as well as both British and American casualties of the Battle of Plattsburgh. The island is the site of a mass grave, believed to contain the remains of roughly 150 of those casualties. The island is infamous locally for its poison ivy, which grows there heavily.