Tortola (tɔrˈtoʊlə) is the largest and most populated island of the British Virgin Islands, a group of islands that form part of the archipelago of the Virgin Islands. It has a surface area of with a total population of 23,908, with 9,400 residents in Road Town. Mount Sage is its highest point at above sea level. Although the British Virgin Islands (BVI) are under the British flag, it uses the U.S. dollar as its official currency due to its proximity to and frequent trade with the U.S. Virgin Islands and Puerto Rico. The island is home to many offshore companies that do business worldwide. Financial services are a major part of the country's economy. On 6 September 2017, the British Virgin Islands were extensively damaged by Hurricane Irma. The most severe destruction was on Tortola. News reports over the next day or two described the situation as "devastation". Dutch Virgin Islands and Sugar plantations in the Caribbean Local tradition recounts that Christopher Columbus named the island Tórtola, meaning "turtle dove" in Spanish. In fact, Columbus named the island Santa Ana. Dutch colonists called it Ter Tholen, after Tholen, a coastal island that is part of the Netherlands. When the British took over, the name evolved to Tortola. On his second voyage for the Spanish Crown to the Caribbean or West Indies, Christopher Columbus spotted what are now called the British and U.S. Virgin Islands. He named the archipelago after the 11,000 virgins of the 5th-century Christian martyr St. Ursula. The Spanish made a few attempts to settle the islands, but pirates such as Blackbeard and Captain Kidd were the first permanent residents. In the late 16th century, the English, who had successfully settled the area contesting claims by the Dutch, established a permanent plantation colony on Tortola and the surrounding islands. Settlers developed the islands for the sugarcane industry, with large plantations dependent on the slave labor of Africans bought from local chiefs and transported across the Atlantic.