Viable sea corridor would cut 4,300 miles from today's route
The Northwest Passage is a sea corridor through Canada's Arctic archipelago – a collection of islands along the northern coast of the North American continent.
European explorers searched in vain for the passage for 300 years, intent on finding a commercially viable and direct western sea route between Europe and Asia.
The first attempt was at the end of the 15th century as European powers dispatched explorers in an attempt to discover a route north and west around North America.
The belief that a route lay to the far north persisted for several centuries and led to numerous expeditions into the Arctic, including the brave but failed attempt by Sir John Franklin and Captain Francis Crozier in 1845. The Northwest Passage was finally navigated in 1903-6 by Norwegian Roald Amundsen in his tiny ship, Gjoa.
The adventurer travelled west and south of Lancaster Sound through Peel Sound and along the western Arctic coast through Queen Maud and Coronation gulfs.
Since that date, several fortified ships have made the journey.
It is thought climate change leading to melting ice may now be opening the passage to more regular shipping.
Estimates as to when summer ice will fully disappear range from 2031-2100.
A commercially navigable Northwest Passage would cut 4,300 miles from the current shipping route between the North Atlantic and Pacific via the Panama Canal.
There is some dispute over who owns the Northwest Passage. Canada maintains it is in Canadian internal waters, but the US and some European countries say the passage is an international strait.