As the search for the Franklin Expedition’s lost ships continues, The Royal Canadian Geographical Society CEO John Geiger joined Prime Minister Stephen Harper and Parks Canada’s Ryan Harris onboard the Sir Wilfrid Laurier coast guard ship in Gjoa Haven, Nunavut, this week.

In 1845, British explorer John Franklin set out to find the Northwest Passage, but the captain and his 128 men never made it. Since then, numerous expeditions have tried to find the ships, the HMS Erebus and HMS Terror, and solve the mystery of their disappearance.

Yet those expeditions have had little success. This August, Parks Canada resumed the hunt for the shipwrecks in what it calls the most comprehensive search yet. Over six weeks, a team of researchers is scouring the Arctic Ocean using a military-grade side-scan sonar, as well as Parks Canada’s new autonomous underwater vehicle and remotely-operate vehicle.

This is the fifth season Parks Canada’s Underwater Archaeology Service has dedicated to the search. So far, the team has surveyed hundreds of kilometres of Arctic seabed. In 2010, underwater archaeologist Ryan Harris made an astonishing discovery when he located the HMS Investigator, a British naval ship sent out to search for Franklin’s ships in 1850.

“The discovery of the Investigator reached an estimated 1.9 billion people globally, so I’m aware of the crushing weight of the public and media interest in the Franklin saga,” Harris said in Canadian Geographic‘s July/August 2013 issue. “To discover one of his ships would be career altering.”

The shipwrecks were jointly named a national historic site in 1992, making it the only undiscovered national historic site in Canada.

Learn more about the search for Franklin’s ships with Canadian Geographic‘s special interactive feature.