Antarctica has no permanent residents, although it contains research stations and field camps that are staffed seasonally or year-round, and former whaling settlements. The largest station, McMurdo Station, has a summer population of about 1,000 people and a winter population of about 200. Approximately 29 nations, all signatory to the Antarctic Treaty, send personnel to perform seasonal (summer) or year-round research on the continent and in its surrounding oceans.