Canadian scientists' announcement Monday that they failed to find the final resting place of British naval hero Sir John Franklin deepened one of the most enduring mysteries of the Arctic.

In May 1845, Franklin set sail from England with 134 men aboard two ships, the Terror and Erebus, to search for the fabled Northwest Passage through the Canadian Arctic to the Pacific Ocean. Five sailors left the ship in Greenland. The rest were never heard from again.

Last week, a six-man government survey team, supported by the Canadian Coast Guard vessel the Sir Wilfrid Laurier and its near 50-man crew, surveyed hundreds of square miles of frigid sea floor hoping to succeed where some 100 other expeditions failed—discovering the fate of the ships and a crew whose demise has been attributed to factors from lead poisoning to cannibalism....