Ripple Rock, an underwater threat to navigation in the Seymour Narrows in Canada is destroyed in a controlled explosions.

Ripple Rock, an underwater mountain within Seymour Narrows near Campbell River BC, was a marine hazard responsible for more than 20 large vessels and at least 100 smaller vessels sinking or being damaged. Before its destruction in 1958, Ripple Rock claimed at least 114 lives.

A Marine Commission’s findings brought a recommendation to remove Ripple Rock as early as 1931, but it was 1942 before this was finally authorized. Despite the extreme hazard the rock created, its removal was bitterly opposed by some, who had envisioned it as a bridge support for a railroad connecting Vancouver Island to the mainland.

The following year, a drilling barge 46 metres long was floated over the rock, held in place by one and half inch steel cables attached to six concrete anhors totaling 1,100 tons.The plan was to drill holes into the top of the rock, fill it with explosives and blast Ripple Rock away bit by bit. The enormous drilling barge quivered and tossed in the violent water, the anchor lines vibrating continually. The attempt failed as anchor lines broke at an average of one every 48 hours.

A second plan was made in 1945 that attempted to hold the drill barge in position by attaching it to two enormous steel overhead lines, each weighing 11 tons. The 3,500 foot cables were stretched across Seymour Narrows 135 feet above high water. Again, water turbulence severely hindered the operation; of the estimated 1,500 drill holes needed only 139 were drilled and 93 blasted, before the contract was terminated.

Eight years later the National Research Council directed a feasibility study on tunnelling to the rock. The idea was to sink a shaft from Maud Island, go under Seymour Narrows, and up into the peaks of Ripple Rock. The underground approach was recommended and Dolmage and Mason Consulting Engineers were retained to plan the project.