Palmer Station is located by Hero Inlet, South Arthur Harbor, a protected harbor on the southwest coast of Anvers Island off the Western Antarctic Peninsula. Palmer is one of three U.S. Antarctic stations governed by the Antarctic Treaty. The station, built on solid rock near a glacier, is a cluster of approximately five buildings. The station operates in conjunction with a research vessel. Since the late 1990s the ARSV Laurence M. Gould has conducted year-round polar operations, sailing frequently between Punta Arenas, Chile and Palmer Station. Approximately 40-45 people occupy Palmer in the summer. The winter-over population varies from 15 to 30.