The Marshall Islands, formally the Republic of the Marshall Islands, is a Pacific Ocean island nation located near the Equator and just west of the International Date Line. Geographically, the nation is part of Micronesia's broader island group. The country's 58,413 inhabitants are dispersed across 29 coral atolls and 1,156 individual islands and islets. Majuro is the capital and largest city. With 97.87% of its territory made up of water, it is the most water-rich sovereign state in the world. Wake Island to the north, Kiribati to the southeast, Nauru to the south, and Federated States of Micronesia to the west share maritime borders. Majuro is home to 52.3% of Marshall Islanders. According to United Nations data, the population in 2018 was estimated to be 58,413. In 2016, urbanization was characterized as 73.3% of the population. The Marshall Islands have a population density of 295 people per square kilometer, with a predicted 2020 population of 59,190. Micronesians arrived in the Marshall Islands in canoes around the second millennium BC, with interisland navigation allowed by conventional stick charts. They finally made their home here. Europeans first visited the archipelago in the 1520s, beginning with Ferdinand Magellan, a Portuguese explorer in Spain's service, Juan Sebastián Elcano, and Miguel de Saavedra. In August 1526, Spanish explorer Alonso de Salazar reported seeing an atoll. Other Spanish and English ships embarked on similar expeditions. John Marshall, who visited in 1788, gave the islands their name. The inhabitants referred to the islands as "jolet jen Anij" in the past. Spain claimed the islands in 1592, and European powers recognised its sovereignty in 1874. Since 1528, they had been officially a part of the Spanish East Indies. Later, in 1885, Spain sold some of the islands to the German Empire, and they became part of German New Guinea that year, run by the island's trading companies, especially the Jaluit Company. The Marshall Islands were occupied by Japan during World War I, and the League of Nations merged them with other former German territories to create the South Seas Mandate in 1920. In 1944, the United States took possession of the islands as part of the Gilbert and Marshall Islands campaign during World War II. Nuclear tests on the Bikini Atoll began in 1946 and ended in 1958. In 1965, the United States founded the Congress of Micronesia as part of a strategy to give Pacific islands more autonomy. In May 1979, the Marshall Islands gained independence from the Trust Territory of the Pacific Islands, whose constitution and president were officially recognised by the United States. In a Compact of Free Association with the United States, full sovereignty or self-government was achieved. Since 1983, the Marshall Islands has been a member of the Pacific Community, and since 1991, it has been a member of the United Nations.