When ships were the only means of long distance travel, a journey from Western Europe to the Orient meant taking a long and dangerous route around either the Cape of Good Hope at the southern tip of Africa, or Cape Horn at the southern tip of South America.

It was hoped that a Northwest Passage through the Arctic would link the Atlantic and Pacific oceans for a shorter route from Europe to Asia.

The search began as soon as Columbus proved that mariners would not fall off the edge of a flat Earth, and it continued for almost 400 years.

The passage was finally discovered in 1905, but as the sea is frozen over for most of the year, it is not very practical. In 1969 a massive tanker set out to test the route for the shipment of Alaskan crude oil to eastern refineries, but one trip was enough - it took months to repair the battered ship.

However, recent climate changes in the Arctic suggest that there will be a 50% reduction in sea ice within a century, and the Northwest Passage could open up as a practical shipping route within 50 years - about 550 years after the search began, and 150 years after it was first discovered!