For centuries before the Panama Canal, Magellan’s waterway was the only water route between the Atlantic and the Pacific, and therefore the center of trade between East and West. European nations placed the utmost importance on the passage, and while Magellan did not set out specifically to find it (as the expeditions to the Northwest Passage had), his discovery was monumental nevertheless.

On this day, November 1, in 1520, Magellan’s fleet of four ships, down from the five that began the circumnavigational expedition, finally found a passage west through the South American continent.

Magellan at first named the waterway Estrecho de Todos los Santos (Strait of All Saints) as it took place on the holiday of All Saints Day, but the name was changed later to honor the explorer who first discovered it. The name Magellan gave to the new body of water the straits did stick — after the burly, chopping Atlantic, the new sea (he thought it was only a small sea) the calm waters inspired the name “Pacific.”