Vancouver Island

To make this passage safe, engineers tunneled under the seabed and blew the top off a mountain nobody could see.

Ripple Rock was a twin peaked summit sitting about three metres below the surface at low tide in Seymour Narrows, the bottleneck near the north end of this board. Accounts of what it cost vary. Some sources count 119 vessels sunk, others separate twenty large ships from about a hundred smaller ones. The figure of 114 lives is consistent across all of them.

There was no reaching it from the water, because the current runs too hard through the narrows. So from 1955 crews sank a shaft about 150 metres down through Maud Island, drove a tunnel roughly 760 metres out beneath the seabed, then turned up inside the rock and packed the chambers with 1,375 tonnes of explosive.

It went off on 5 April 1958, twenty seven months after the digging started. CBC carried it live, one of the first coast to coast broadcasts in the country.