In seeking to solve one shipwreck mystery, underwater explorers happened upon another.

The quest — which unfolded on the Discovery Channel’s “Expedition Unknown,” a reality TV series — starts with the adventure show host, Josh Gates, paddling in a bright yellow kayak through the Soo Locks as he looks for World War I-era French warships lost in the Great Lakes, the Inkerman and Cerisoles.

They are two of three French minesweepers that were built in Canada’s port city of Thunder Bay, Gates said, and were headed together through the Great Lakes to the Atlantic and then Europe. Instead, in a 1918 storm, they sank, taking the lives of nearly 80 mariners and creating one of the greatest vanishing ship mysteries ever.

Gates — who worked with the Great Lakes Shipwreck Historical Society — didn’t find the French vessels.

But he did uncover an even older ship, the long-missing tugboat, the Satellite, that sank June 21, 1879, nearly 40 years before the minesweepers. The Satellite was a find that the historical society said last week it was proud to announce.

The search also has thrust Michigan’s shipwreck society — founded in 1978 by a group of divers, teachers and educators to explore shipwrecks — into the national spotlight, and when the TV show’s June 21 episode debuted, it revealed a ship that no one alive had seen before.

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First, a Great Lakes history lesson

Gates — who styles himself as an “international adventurer” traveling “to the ends of the earth” looking into unsolved mysteries — explained during the fifth episode of the eleventh season of “Expedition Unknown” why the minesweepers were in the Great Lakes and why it matters.

During the first world war, Gates said, Germany was laying tens of thousands of mines in the English Channel and the French Navy was building minesweepers to destroy the deadly explosives. The last three of these ships headed to Europe, but two sank.

There was no wreckage.

This is where Gates turns to the Great Lakes Shipwreck Museum at Whitefish Point, where the historical society also is based. The museum’s Executive Director Bruce Lynn told Gates the minesweepers were built in Canada, because the French shipbuilders were overwhelmed.