Speculation over the existence of a 'southern land' was not confirmed until the early 1820s when British and American commercial operators and British and Russian national expeditions began exploring the Antarctic Peninsula region and other areas south of the Antarctic Circle. Not until 1840 was it established that Antarctica was indeed a continent and not just a group of islands. Several exploration 'firsts' were achieved in the early 20th century. Following World War II, there was an upsurge in scientific research on the continent. A number of countries have set up a range of year-round and seasonal stations, camps, and refuges to support scientific research in Antarctica. Seven have made territorial claims, but not all countries recognise these claims. In order to form a legal framework for the activities of nations on the continent, an Antarctic Treaty was negotiated that neither denies nor gives recognition to existing territorial claims; signed in 1959, it entered into force in 1961.
Climate: Severe low temperatures vary with latitude, elevation, and distance from the ocean; East Antarctica is colder than West Antarctica because of its higher elevation; Antarctic Peninsula has the most moderate climate; higher temperatures occur in January along the coast and average slightly below freezing. Terrain: About 98% thick continental ice sheet and 2% barren rock, with average elevations between 2,000 and 4,000 metres; mountain ranges up to nearly 5,000 metres; ice-free coastal areas include parts of southern Victoria Land, Wilkes Land, the Antarctic Peninsula area, and parts of Ross Island on McMurdo Sound; glaciers form ice shelves along about half of the coastline, and floating ice shelves constitute 11% of the area of the continent.
Fishing off the coast and tourism, both based abroad, account for Antarctica's limited economic activity. Antarctic fisheries in 2005-06 (1 July-30 June) reported landing 128,081 metric tons (estimated fishing from the area covered by the Convention on the Conservation of Antarctic Marine Living Resources (CCAMLR), which extends slightly beyond the Antarctic Treaty area). Unregulated fishing, particularly of Patagonian toothfish (Dissostichus eleginoides), is a serious problem. The CCAMLR determines the recommended catch limits for marine species. A total of 36,460 tourists visited the Antarctic Treaty area in the 2006-07 Antarctic summer, up from the 30,877 visitors the previous year (estimates provided to the Antarctic Treaty by the International Association of Antarctica Tour Operators (IAATO); this does not include passengers on overflights). Nearly all of them were passengers on commercial (non-governmental) ships and several yachts that make trips during the summer. Most tourist trips last approximately two weeks.