1497: The Venetian navigator in the service of England, John Cabot, is the first to propose the idea of a route to the East via the far north of Europe. He is commissioned by King Henry VII to discover it.
1539: Hernán Cortés, a leading figure in the Spanish conquest of Central and South America, sends explorer Francisco de Ulloa to the west coast of the United States. De Ulloa concludes that there is an island of California, marking the beginning of a route that could potentially extend much further north.
1576–1747: Several navigators, including Martin Frobisher, Jacques Cartier, Henry Hudson, and Henry Ellis, attempt different routes to discover the passage. Explorations up the Saint Lawrence River – aimed at confirming whether it splits the American continent – and investigations near Greenland fail to lead these adventurers to the fabled destination.
1775: The merchant ship Octavius is found drifting near Greenland, with the frozen bodies of the crew still on board. It had disappeared 13 years earlier, trapped in Arctic ice. It is believed to be the first vessel to have successfully crossed the fabled passage.
1776: British explorer James Cook sets out on an expedition, but upon reaching beyond 70°N and encountering only icebergs, he turns back.
1845–1846: British expeditions led by John Franklin and Robert McClure end in failure, involving forced wintering and many human losses. However, evidence of these expeditions has been found, particularly on King William Island, in the middle of the passage.
1903–1906: Norwegian explorer Roald Amundsen becomes the first to successfully navigate the passage from east to west during his Arctic expedition.