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Each cable contains 96 pairs of glass filament strands, with each of the 192 individual strands measuring about one human hair in diameter. The cable is insulated by polyurethane and other materials.

Most submarine cables have the diameter of a garden hose, but the Crosslake cable had additional layers of yellow tubing, giving it a two-inch diameter, because Lake Ontario is shallow compared to an ocean, and that exposes the cable to a higher risk of damage from fishing, ship anchors or other human activities.

Most people don't understand it, but subsea cables really are the plumbing of the internet Mike Cunningham, CEO, Crosslake Fibre

If a cable does break, it can be pulled onto a ship for repairs, which can take two weeks for cables at depths of seven kilometres or two days for shallower projects such as Crosslake, the ship’s chief officer Geoffrey Dunlop explained on the tour.

Then there’s the ship. Built in the United Kingdom in 1989, the Intrepid was converted to do installations after IT International Telecom bought it in 2004. It built a new deck on the back with a cable burial plow, an A-frame and enough room for big spools of cable.

To lay cable on a seabed, it is first unspooled and sent along tire rollers that load it into a 17-tonne plow on the stern. The A-frame is lowered from the back of the ship in order to lower the plow to the bottom. At this point, the crew “walks” the ship forward to get the appropriate tension on the wires towing the plow.

As the plow digs a trench, a piece of equipment pushes the cable down so it stays put until the bottom of the sea bed — or lake bed in this case — folds in on itself and covers the cable.