The theory that the North Pole region might be a practical sea route goes back to at least the 16th century, when it was suggested by English cartographer Robert Thorne (1492-1532).

It was believed that once a ship broke through the regions of thick ice that had stopped previous explorers, a temperate sea would be found beyond it.

Reports of open water by earlier explorers, such as Elisha Kent Kane and Isaac Israel Hayes, fueled optimism in the theory in the 1850s and 1860s.

Support faded when George W. De Long sailed USS Jeannette into the Bering Strait in the hope of finding an open gateway to the North Pole and was met by a sea of ice.

After a long drift, pack ice crushed the Jeannette, and her survivors returned home with first hand accounts of an ice-covered polar sea.