The British Virgin Islands' geography: steep volcanic peaks and one flat coral island

How a drowned ridge made the islands

The British Virgin Islands are the eastern part of the Virgin Islands archipelago, between the Caribbean Sea to the west and the North Atlantic to the east. With Puerto Rico and the US Virgin Islands they are the high points of one underwater bank, which stood above the sea as a continuous land mass during the Pleistocene and was raised by the collision of the Caribbean and North American plates. The nearest neighbour is the US Virgin Islands, a few miles to the west; Puerto Rico lies about 95 kilometres away and Anguilla about 150 kilometres to the east-south-east.

How many islands there are depends on who counts. The United Nations working paper of 2026 describes some 60 islands, islets and cays, of which twenty are inhabited. The Wikipedia accounts give about 60 islands with about 16 inhabited, or 16 inhabited and more than 20 uninhabited, and the National Parks Trust's own island pages run to dozens of named cays. The land area is given as 153 square kilometres by the United Nations and in the territory's record, and as 151 by the geography article Wikipedia carries.

The sea is far larger than the land. The territorial sea runs to 12 nautical miles and the exclusive fishing zone to 200, and the United Nations gave the exclusive economic zone as 80,117 square kilometres in its 2026 paper. The coastline of all the islands together is about 80 kilometres.

What the high islands are made of

Most of the islands are volcanic in origin and steep. Apart from Anegada they are built of pyroclastic rock with mixed deposits of diorite and tonalite, both rocks that cooled from magma below ground. Tortola lies near an earthquake fault, and minor earthquakes are common there; an earthquake and tsunami struck the island in 1867.

The granite of Virgin Gorda tells the deeper story. The National Parks Trust describes the boulders of the Greater Baths as granodiorite, a coarse-grained intrusive rock formed by the slow cooling of magma in chambers under the volcanoes of an island arc. Where the North American Plate sinks below the Caribbean Plate, partial melting fed those chambers; the magma slowly changed towards granite and crystallised 5 to 10 kilometres below the surface, forming what the Trust calls the Baths Pluton. The main eastern part of the Virgin Island Batholith formed over about 6 million years in the Middle to Late Eocene. Uplift and erosion later brought it to the surface, and weathering broke it into the rounded blocks now piled on the shore, some as large as 40 feet across. On the beach at the south-western tip of Virgin Gorda the blocks lean together into grottoes and pools open to the sea. The same tumbled boulders cover Fallen Jerusalem, a deserted island off the southern tip, and on the cliffs of the south-east the ruins of the Copper Mine stand among outcrops carrying quartz and feldspar along with tin, copper and clay minerals.

The four main islands account for most of the land:

Tortola is about 20 kilometres long and 5 kilometres wide, and two figures circulate for its summit: 521 metres in the territory's main Wikipedia articles and 530 metres in the article on the island itself. Neither names the survey behind its figure.

Why Anegada looks like no other island

Anegada stands apart from the rest of the group. It is geologically distinct, a flat island of carbonate reef deposits where everything else is volcanic rock, and the Tourist Board gives its highest point as 28 feet above sea level. It covers 36 square kilometres.

The island is ringed by reefs, underwater caves and tunnels, and the waters around it hold the wrecks of Spanish galleons, American privateers and British ships. Inland the ground holds salt ponds. Flamingos once lived there by the hundreds and were hunted out; in 1991 the Bermuda Aquarium, Museum and Zoo donated a captive flock, which the National Parks Trust released on Anegada, and the birds have since bred in the wild around Flamingo Pond.

Anegada also keeps an animal found nowhere else. The National Parks Trust began a rehabilitation programme in 1997 for the Anegada rock iguana, Cyclura pinguis, whose numbers were falling fast because of starvation, habitat loss and hunting by wild cats. A headstart facility built with the Iguana Specialist Group raises juveniles taken from high-risk areas, feeding them daily and measuring them monthly, with release into the wild as the long-term aim.

How the forest and scrub cover the hills

The islands lie in two terrestrial ecoregions, the Leeward Islands moist forests and the Leeward Islands xeric scrub. Forest covered about 24% of the land in 2020, 3,620 hectares against 3,710 hectares in 1990. A land-use figure from 2005 put arable land at 20% and permanent crops at 6.67%, with the remaining 73.33% in other uses.

The higher ground holds what forest remains. Sage Mountain on Tortola became the territory's first national park after Laurance Rockefeller paid for the land to be bought from farmers and given to the government. Gorda Peak, the summit of Virgin Gorda, was donated by Rockefeller in 1974, and the National Parks Trust describes it as one of the last remaining examples of Caribbean dry forest in the region. Lower down, sugar cane was once farmed on terraced slopes: an eighteenth-century windmill at Mount Healthy ground cane from a 250-acre plantation on Tortola's north shore.

Where the water shelters the boats

The islands enclose a set of sheltered waters, and these shape the way the territory is used. The main channel through the group is named after Francis Drake, who anchored in North Sound on Virgin Gorda in 1585. North Sound, at the north-east end of Virgin Gorda, is bordered by four islands and connecting reefs that keep it calm, and its protected waters cover more than 3,000 acres. Biras Hill, at 435 feet, stands over its eastern anchorage.

Road Town, the capital, sits on the horseshoe-shaped Road Harbour in the middle of Tortola's south coast. Part of it is made land: Wickham's Cay, a development of 28 hectares, was built on two areas reclaimed from the sea together with a marina, and it holds the newest commercial and government buildings.

Tortola's north coast is a string of bays and beaches facing the Atlantic: Smuggler's Cove, Long Bay, Cane Garden Bay, Brewer's Bay, Josiah's Bay and Lambert Beach. Shark Bay National Park runs from the ridge at Anderson Point down to the bay at the foot of the Mount Healthy ghut.

The smaller islands carry their own marine features. The wreck of the RMS Rhone lies in about 20 to 80 feet of water in Lee Bay off Salt Island, inside a marine park that extends west to the island of Dead Chest. The Tobago Cays, at the north-western corner of the group, are ringed by cliffs that drop to depths of up to 50 metres. Prickly Pear, a bird sanctuary in North Sound, is fringed on its northern side by the Bank Barrier Reef, with Eustatia, Mosquito and Necker islands nearby. Diamond Cay, between Little Jost Van Dyke and Jost Van Dyke, has bare rock cliffs on its windward side and sandy beaches on its leeward side.

How the climate and hurricanes set the year

The climate is usually classed as tropical savanna, moderated by the trade winds; the Road Town article gives it as tropical monsoon on the Köppen scale, bordering on savanna and on a relatively dry rainforest. Temperature varies little through the year. In Road Town typical daily maxima are around 32 °C in summer and 29 °C in winter. The sources disagree on the minima, giving either 26 °C in summer and 23 °C in winter or 24 °C and 21 °C, and they disagree on rainfall too: about 1,150 millimetres a year in the territory's main articles, about 1,250 in the article on Road Town. Rain is heavier in the hills and lighter on the coast. The wettest months on average are September to November, and the driest are February and March.

The hurricane season runs from June to November. Hurricane Irma made landfall on Virgin Gorda at 1630 UTC on 6 September 2017 as a category 5 hurricane with winds estimated at 155 knots by the US National Hurricane Center, which recorded four deaths in the territory and numerous buildings and roads destroyed on Tortola. Hurricane Maria followed fourteen days later, its eye passing south of St Croix. The history article records the hurricanes of the nineteenth century that finished the sugar estates.

Who looks after the protected land and sea

The National Parks Trust of the Virgin Islands was set up under the National Parks Ordinance of 1961. It managed one park, Sage Mountain, in 1964 and twenty-one in 2017, and its pages list five parks on Tortola, six on Virgin Gorda and nine on the other islands.

The cays matter for seabirds. West Dog, a steep volcanic island among The Dogs west of Virgin Gorda, is a nesting site for bridled terns, sooty terns, red-billed tropicbirds and the endangered roseate tern. Cam Bay on Great Camanoe has a salt pond that traps sediment from freshwater run-off before it reaches the reef, and it draws migratory wading birds such as black-necked stilts and white-cheeked pintails, while green turtles feed on the sea grass in the lagoon. Sandy Cay, 13.57 acres, was owned for 40 years by Laurance Rockefeller, whose team planted more than 200 palms and began bird and turtle monitoring there.

Where people live on so little land

The 2010 census counted 28,054 people, 23,491 of them on Tortola, and the United Nations found that 83% of the population lived on Tortola that year. Residents of Jost Van Dyke, Anegada, Cooper Island, Great Camanoe and the other small islands made up just over 2% of the total.

The population has grown since. The territory's record gives 39,369 people in 2023 and the United Nations working paper 39,471 in 2024. Growth has not been steady: the territorial government's review, cited by the United Nations in 2025, puts normal growth at 2.6% a year, a fall of 9.1% in 2017 after the two category 5 hurricanes, a rise of 3.0% in 2018 as people returned, and growth of 0.1% in 2022. Spanish Town on Virgin Gorda, also known as The Valley, was the original capital; the island was mined for copper from the seventeenth to the nineteenth century, until the mine closed in 1867.

Land is short for other uses too. The Pan American Health Organization, cited by the United Nations in 2026, notes that the territory has little land available for landfill and that the rolling terrain makes landfills hard and expensive to engineer. Most waste is burned at the Pockwood Pond incinerator on Tortola, which can take 100 tons a day, with further landfill on Tortola, Virgin Gorda and Anegada. The travel article follows the ferry routes between the islands.