Stretching 1,200 kilometres from the Great Lakes to the Atlantic, the St. Lawrence was the highway into a continent — and for several thousand ships, it was the last place they ever sailed.

The St. Lawrence is not a gentle river. It narrows without warning, deepens without sign, and moves with a cold indifference to anything floating on its surface.

For three centuries it was the highway into a continent — for explorers, settlers, coal, iron, grain. Since 1959, when the Seaway opened, it became a gateway to the heart of North America. Millions of tonnes of cargo pass through it every year.

Not all of it arrived.

It is estimated that several thousand ships have been lost in these waters. Fewer than 100 have ever been formally documented.

Three of the largest ships ever lost in the St. Lawrence. Three collisions. Three nights of fog.

The river doesn't need a storm to take a ship. It only needs darkness, a current running sideways, and one vessel that doesn't know another is there.

The RMS Empress of Ireland is outbound from Québec City, carrying 1,477 people. Somewhere in the fog off Sainte-Luce, a Norwegian coal carrier called the Storstad is moving upriver, loaded and riding low.

They collide amidships. The Empress lists immediately. Portholes — left open in the summer heat — flood the lower decks in seconds.

Fourteen minutes later, she is on the bottom.

1,012 people are dead. More, proportionally, than the Titanic — which sank two years before and has never been forgotten. The Empress sank on a Wednesday. By Saturday, the newspapers had moved on. Six weeks later, the war started.

History has almost no memory of this.

The MV Tritonica is an ore carrier, 161 metres long, the first vessel of its kind to pass through the St. Lawrence Seaway when it opened four years earlier. Off Petite-Rivière-Saint-François, in the dark, it collides with the SS Roonagh Head.

It sinks in ten minutes.

In the village onshore, people heard it happen — engines, sirens, the metallic crash of two hulls meeting. Thirty-three sailors died, most of them Chinese. It was the worst civilian maritime disaster on the St. Lawrence since the Empress of Ireland, half a century before.

In the days that followed, bodies came ashore at Île-aux-Coudres, downstream. The wreck posed a danger to navigation. It was dynamited and buried in a dredged trench on the riverbed.

No one came to look until 2016.

The SS Leecliffe Hall is two football fields long. 222.5 metres. 18,071 gross tons, loaded with 24,500 tonnes of iron ore. It was built at the same Scottish yard as the Empress of Ireland.

Off Île-aux-Coudres, it collides with the Greek freighter MV Apollonia. The ships lock together. Neither sinks. The crew is evacuated — safely, all of them.

Then three men went back.

They wanted to save the ship. While they were aboard, the hull broke apart. The Apollonia limped away with a shattered bow. The Leecliffe Hall went down in pieces.

Two of the three bodies were never recovered.

These are three of the ones we know. Formally documented. Named. Dived.

The rest — perhaps a thousand, perhaps several thousand — lie unnamed in the cold and the current. Bumps in the sand. Pieces of iron. Ships that no one recorded losing.

The St. Lawrence doesn't give up what it takes.