Part of the Stewart B. McKinney National Wildlife Refuge, the island is controlled by the U.S. Fish and Wildlife Service, which closes it to the public most of the year in order to protect the bird nesting areas, The public is usually restricted to the around the Sheffield Island Light, which the Norwalk Seaport Association maintains, although a trail has been created to allow the public controlled access. In the summer, the association arranges tours for people to visit the lighthouse and picnic there. On Thursday nights, clambakes and on Friday nights, sunset cruises are held. The lighthouse, built in 1868, was a navigational aid until about 1900. Sheffield Island is at .