Ripple Rock is an underwater mountain that had two peaks (9 feet and 21 feet below the surface) in the Seymour Narrows of the Discovery Passage in British Columbia, Canada, a part of the marine trade route from Vancouverand coastal points north. The nearest town is Campbell River. Only 2.7 metres (9 feet) underwater at low tide, it was a marine hazard in what the explorer George Vancouver described as “one of the vilest stretches of water in the world.” The hazard was not only hitting the rock but also big, dangerous eddies caused by tidal currents round the rock. Ships using the strait preferred to wait until slack tide.
Its top was removed by a planned explosion on 5 April 1958. This is a National Historic Event in Canada. The Ripple Rock explosion was seen throughout Canada, live on CBC Television. It was one of the first live coast-to-coast television broadcasts of an event in Canada.