Cape Horn is the southernmost headland of the Tierra del Fuego archipelago of southern Chile, and is located on the small Hornos Island. Although not the most southerly point of South America (which are the Diego Ramírez Islands), Cape Horn marks the northern boundary of the Drake Passage and marks where the Atlantic and Pacific Oceans meet.

Cape Horn was discovered and first rounded by the Dutchman Willem Schouten, who named it About this sound Kaap Hoorn (help·info) after the city of Hoorn in the Netherlands. For decades, Cape Horn was a major milestone on the clipper route, by which sailing ships carried trade around the world. The waters around Cape Horn are particularly hazardous, owing to strong winds, large waves, strong currents and icebergs; these dangers have made it notorious as a sailors' graveyard.

The need for ships to round Cape Horn was greatly reduced by the opening of the Panama Canal in 1914. Sailing around the Horn is widely regarded as one of the major challenges in yachting. Thus a few recreational sailors continue to sail this route, sometimes as part of a circumnavigation of the globe. Almost all of these choose routes through the channels to the north of the Cape. (Many take a detour through the islands and anchor to wait for fair weather to visit Horn Island, or sail around it to replicate a rounding of this historic point). Several prominent ocean yacht races, notably the Volvo Ocean Race, the VELUX 5 Oceans, and the Vendée Globe, sail around the world via the Horn. Speed records for round-the-world sailing are recognized for following this route.