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The Ripple Rock Blast
Special thanks to the CBC for the Ripple Rock Broadcast

BC Archive picture of Ripple Rock
BC Archive picture of Ripple Rock wreckage
BC Archive picture of Ripple Rock wreckage
Seymour Narrows
Sign about Seymour Narrows
Seymour Narrows from a distance

Ripple Rock (Seymour Narrows)

Near Quadra Island

Seymour Narrows was once considered the most dangerous stretch of water on the inside passage of Vancouver Island. Between 1850 and 1953 more than 100 ships struck the rocks that lie just beneath the surface, and for many, this would be where they sank. Responsible was a series of craggy rocks lying just beneath the surface that, at slack water, are invisible to the eye. When the tide is moving however, the area would turn into a churning mass of water, belying the location of the highest points, as well as increasing the danger due to swirling currents. In 1953 the BC government decided to do something about the problem, and had Ripple Rock blasted apart in what turned out to be the largest peacetime non-nuclear explosion in the world.



CBC Ripple Rock Broadcast
In 1875, the steamship USS Sarnac claimed the dubious honour of becoming the first vessel to sink as a result of hitting Ripple Rock. It would be the beginning of the long and illustrious career of Seymour Narrows as “one of the vilest stretches of water in the world,” so called by Captain George Vancouver. From 1875 to 1958, Ripple Rock claimed 120 different vessels, and over 110 lives, earning its reputation as one of the most hostile pieces of water to navigate in North America.

Since the early 1900’s there had been pressure on the BC Government to somehow lessen the risk of traveling the passage, which was a key channel in navigating the inside passage of Vancouver Island. Despite many feasibility studies, the two World Wars proved to be a higher priority, and the first major attempt to remove some of the rock wasn’t until 1943.
Having had enough of the constant loss of life on the rock, the BC Government sent a huge barge and drilling rig to drill into the rock and place explosive charges to remove the top layer. Unfortunately, the current was so strong in the passage that the inch thick steel cables securing the barge to the bottom of the narrows continually broke, making the drilling impossible. Another attempt was made using the same method in 1945, but it too was foiled by the immense tidal flow.

The idea was shelved for almost a decade, when a team of scientists from the National Research Council declared they thought the answer was tunneling under the rock from Maud Island, and laying explosive charges from beneath, to avoid having to deal with the tidal currents. Work began in 1955, and after 27 months and 1375 pounds of Nitramex 2H, a network of tunnels packed with explosives were ready to go. At 9:31am on April 5, 1958, Ripple Rock blasted its way into history, with over 370,000 tons of rock hurtling into the air, never to endanger another ship.   

The massive success of the project was a relief to mariners all up and down the pacific coast, and, once verified, was declared the largest ever non-nuclear explosion in the world, a record that still stands. The demolition was shown coast to coast by the CBC, in one of the first national broadcasts ever, and showed Canada not only the technical prowess of the demolition engineers, but the beginning of the nation-wide era of broadcasting.


50°07’55”N 125°21’12”W


Despite its prominence in history, Ripple Rock is a rather normal feature on Vancouver Island. Underwater peaks exist in many places, and it is only their location that made the two at Ripple Rock a hazard.

The two peaks sat about 30 meters apart, leaving a narrow channel to one side through which boats had to pass. The tidal current, which at times could run faster than ten knots, pulled sideways across the peaks, creating unpredictable swirls, eddies, and whirlpools that sucked boats onto the rocks. The danger was compounded by the fact than once a boat had hit the peaks and suffered damage, the current would continue to drag the disabled vessel out into deeper water, where they would almost all sink.

Pre-blast, at low tide, the rocks were only nine feet under water. After the explosion, the highest point was more than 45 feet deep at low tide, a much safer margin of error. Though the danger from hitting the rocks is now non-existent, the current through the narrows is still treacherous, moving quickly and unpredictably, due still to the upheaved nature of the seafloor.




Lying between Quadra Island and Vancouver Island, Seymour Narrows remains a very busy shipping and transport corridor. Access is easy by boat from Campbell River, and there is a popular hiking trail on the Vancouver Island side that starts just north of Campbell River, and winds about 4 km up to a viewpoint overlooking the narrows. There is a marked trailhead and parking lot on the side of highway 19.


Web site ©: The Institute for Coastal and Oceans Research (ICOR) at the University of Victoria, British Columbia Canada.