OTTAWA -- A Canadian search team has unlocked one of the world's great exploration mysteries with the discovery of one of two lost ships from Sir John Franklin's doomed Arctic expedition.

The remarkable find completes one half of a puzzle that long ago captured the Victorian imagination and gave rise to many searches throughout the 19th century for Franklin and his crew.

The search team confirmed the discovery on Sunday using a remotely operated underwater vehicle recently acquired by Parks Canada. They found the wreck 11 metres below the water's surface.

It is not known yet whether the ship is HMS Erebus or HMS Terror.

Prime Minister Stephen Harper, who recently came close to the search area on his annual northern trip, could barely contain his delight Tuesday as he delivered news of the "great, historic" breakthrough.

"For more than a century, this has been a great Canadian story and mystery," Harper said.

"I'd say it's been the subject of scientists and historians and writers and singers. So I think we have a really important day in mapping together the history of our country."

The ship appears to be well-preserved. A sonar image projected at a media conference showed the ship five metres off the sea floor in the bow and four metres in the stern.

Ryan Harris, a senior underwater archeologist and one of the people leading the Parks Canada search, said the sonar image showed some of the deck structures are still intact, including the main mast, which was sheared off by the ice when the ship sank.

The contents of the ship are most likely in the same good condition, Harris added.

The discovery came a day after a team of archeologists found a tiny fragment from the expedition in the King William Island search area. Until Tuesday, those artifacts were the first ones found in modern times.

The two ships of the Franklin Expedition and their crews disappeared during an 1845 quest for the Northwest Passage.

They were the subject of many searches throughout the 19th century, but the mystery of exactly what happened to Franklin and his men has never been solved.

The expedition has been the subject of songs, poems and novels ever since.

"We've got half the story here," said John Geiger, president of the Royal Canadian Geographical Society.

"It's very exciting. It's a big break."

Since 2008, Parks Canada has led six major searches for the lost Franklin ships. Four vessels -- the Canadian Coast Guard ship Sir Wilfrid Laurier, the Royal Canadian Navy's HMCS Kingston and vessels from the Arctic Research Foundation and the One Ocean Expedition -- led the search this summer.

Officials recently said it was only a matter of time before the ships were found.

On his annual tour of the North last month, the prime minister got a first-hand look at some of the tools being used in the hunt for the ships. Harper helped lower an autonomous underwater vehicle into the frigid water near Pond Inlet.

The Conservatives have made Arctic sovereignty a key theme since coming to power in 2006. Harper recently told journalists aboard HMCS Kingston the Franklin search was part and parcel of asserting Canada's control over its North.

"It ultimately isn't just about the story of discovery and mystery and all these things," Harper said last month.

"It's also really is laying the basis for what's, in the longer term, Canadian sovereignty."

One observer says the Franklin search has more to do with Canadian nationalism than Arctic sovereignty.

"The discovery of two historical wrecks from the 1840s that sailed under the authority of Britain before Canada was even a state doesn't really extend our claims of control over the waters of the Northwest Passage," said Rob Huebert, an Arctic expert at the University of Calgary.

What the discovery does, Huebert added, is help cement a commitment to developing the North as part of Harper's legacy.

"The Arctic is going to be one of his major legacies when people look back on his leadership period."