The Falklands, which has a total land area is 4,700 square miles (12,173 km2) and a coastline estimated at 800 miles (1288 km), comprise two main islands, West Falkland and East Falkland and about 776 small islands. The islands are heavily indented by sounds and fjords and have many natural harbours. The two main islands are separated by the Falkland Sound which averages 12 miles (20 km) in width. Much of the northern part of the sound which is clear water approaches 40 metres (22 fathoms) in depth, but the southern part, which has many flat islands and some shoals has a number of channels that are much deeper.
East Falkland, which contains the capital Stanley and the British military base at Mount Pleasant, is the more populous of the two main islands.
Both West Falkland and the northern part of East Falkland have mountain ranges that are underlaid with Palaeozoic rock, which, as a result of secondary forces associated with continental drift are at 120° to each other. The highest point of the islands is Mount Usborne, 705 metres (2,313 ft) on East Falkland, while Mount Adam on West Falkland is only 5 metres (16 ft) lower. The southern part of East Falkland, the Lafonia Peninsula, which is connected to the rest of the island by a 4 km narrow isthmus, is dissimilar to the rest of the island. Most of Lafonia is a flat plain underlain by younger Mesozoic rock, but in the north west is Permian rock which similar to that of parts of Ecca Pass in South Africa.
The islands claim a territorial sea of 12 nautical miles (13.8 mi; 22.2 km) and an Exclusive Economic Zone of 200 nautical miles (230.2 mi; 370.4 km), which has been a source of disagreement with Argentina.