We had the chance to explore the west side of Seymour Narrows, one of the most powerful tidal channels on the BC coast—and one of the most historically significant. This is where Ripple Rock once loomed just beneath the surface, a deadly underwater peak that was removed in one of the largest non-nuclear explosions in history back in 1958.
We teamed up with Captain Earl Lowe of Abyssal Dive Charters, who not only helped guide us through the dive site, but also shared a ton of amazing history about Ripple Rock and the surrounding area. His knowledge and experience really brought this dive to life.
Big thanks as well to the Museum at Campbell River for collaborating with us and allowing the use of some incredible archival photos from the Ripple Rock explosion. B Sea Adventure
Seymour Falls
Seymour Narrows is a 5-kilometre (3.1-mile) stretch within Discovery Passage in British Columbia, renowned for its intense tidal currents. Discovery Passage separates Vancouver Island—near Menzies Bay—from Quadra Island, except at its northern end, where Sonora Island forms the eastern boundary. Seymour Narrows begins approximately 18 kilometres (11 miles) from the southern entrance of Discovery Passage, which opens into the Georgia Strait near Campbell River. The narrows are roughly 750 metres (820 yards) wide for most of their length, and tidal currents in the area can surge up to 15 knots (28 km/h or 17 mph).
Seymour Narrows was named in honor of Rear Admiral Sir George Francis Seymour, who led the Pacific Station between 1844 and 1848. Captain George Vancouver once referred to the narrows as “one of the vilest stretches of water in the world.” Despite the removal of Ripple Rock, the area continues to pose significant navigational challenges. In March 1981, the freighter Star Philippine ran aground while passing through the narrows.
Ripple Rock
Ripple Rock was a dangerous underwater twin-peaked mountain located just nine feet below the surface of Seymour Narrows. It posed a major threat to maritime traffic, having caused the sinking of 119 vessels and the loss of 114 lives. One of the earliest recorded casualties was the gunboat USS Saranac. On April 5, 1958, following 27 months of tunneling and engineering efforts, the rock was destroyed using 1,375 tons of Nitramex 2H explosive. This detonation became the largest non-nuclear, planned commercial explosion in North American history. Although the 1917 Halifax Explosion was more powerful, it occurred accidentally and was not intentionally triggered.
The event was broadcast live on Canadian television. The footage is also regularly screened at the Campbell River Museum.
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