northwest passage

noun

1. a ship route along the Arctic coast of Canada and Alaska, joining the Atlantic and Pacific oceans.

noun

1. the passage by sea from the Atlantic to the Pacific along the N coast of America: attempted for over 300 years by Europeans seeking a short route to the Far East, before being successfully navigated by Amundsen (1903–06)

A sea route from the Atlantic Ocean to the Pacific Ocean through northwestern America, often sought by early explorers. There is an actual Northwest Passage, but it requires sailing through far northern waters that are icebound much of the year.