thumb|upright=1.55|The Strait of Magellan
The Strait of Magellan (), also called the Straits of Magellan, is a navigable sea route in southern Chile separating mainland South America to the north and the Tierra del Fuego archipelago to the south. Considered the most important natural passage between the Atlantic and Pacific oceans, the strait is approximately long and wide at its narrowest point. The name of the strait dates to 1520, when the Spanish expedition of the Portuguese navigator Ferdinand Magellan brought the first Europeans to the area.
Magellan's original name for the strait was Estrecho de Todos los Santos ("Strait of All Saints"). The King of Spain, Emperor Charles V, who had sponsored the Magellan-Elcano expedition, changed the name to the Strait of Magellan in honor of Magellan.
The route is difficult to navigate due to frequent narrows and unpredictable winds and currents. Maritime piloting is now compulsory. The strait is shorter and more sheltered than the Drake Passage (the open sea route around Cape Horn), which is beset by frequent gale-force winds and icebergs.
Historically identifiable indigenous ethnic groups around the strait are the Kawésqar, the Tehuelche, the Selkʼnam and the Yaghan people. The Kawésqar lived on the western part of the strait's northern coast. To the east of the Kawésqar were the Tehuelche, whose territory extended to the north in Patagonia. To the south of the Tehuelche across the strait lived the Selkʼnam, who inhabited the majority of the eastern portion of Tierra del Fuego. To the west of the Selkʼnam were the Yaghan people, who inhabited the southernmost part of Tierra del Fuego.
All tribes in the area were nomadic hunter-gatherers. The Tehuelche were the only non-maritime culture in the area; they fished and gathered shellfish along the coast during the winter and moved into the southern Andes in the summer to hunt. The tribes of the region saw little European contact until the late 19th century. Later, European-introduced diseases decimated portions of the indigenous population.
It is possible that Tierra del Fuego was connected to the mainland in the Early Holocene (c. 9000 years BP) much in the same way that Riesco Island was back then. A Selkʼnam tradition recorded by the Salesian missionary Giuseppe María Beauvoir relates that the Selkʼnam arrived in Tierra del Fuego by land and that the Selkʼnam were later unable to return north as the sea had flooded their crossing. Selkʼnam migration to Tierra del Fuego is generally thought to have displaced a related non-seafaring people, the Haush that once occupied most of the main island. The Selkʼnam, Haush, and Tehuelche are generally thought to be culturally and linguistically related peoples physically distinct from the sea-faring peoples.
Magellan led an expedition in the service of the Spanish King, Emperor Charles V, to reach the Spice Islands. His ships became the first to navigate the strait in 1520. The five ships included La Trinidad (110 tons, 55 crew members), under the command of Magellan; La San Antonio (120 tons, 60 crew members) under the command of Juan de Cartagena; La Concepción (90 tons, 45 crew members) under the command of Gaspar de Quesada (Juan Sebastián Elcano served as boatswain); La Victoria (85 tons, 42 crew members) under the command of Luis de Mendoza; and La Santiago (75 tons, 32 crew members), under command of Juan Rodríguez Serrano (João Rodrigues Serrão). Before the passage of the strait (and after the mutiny in Puerto San Julián), Álvaro de Mesquita became captain of the San Antonio, and Duarte Barbosa of the Victoria. Later, Serrão became captain of the Concepcion (the Santiago, sent on a mission to find the passage, was caught in a storm and wrecked). San Antonio charged to explore Magdalen Sound, failed to return to the fleet, instead sailing back to Spain under Estêvão Gomes, who imprisoned the captain Mesquita.
Magellan's ships entered the strait on All Saints' Day, 1 November 1520. Magellan named the Strait Estrecho de Todos los Santos ("Strait of All Saints") and
planted a flag to claim the land on behalf of the King of Spain.