Ripple Rock

Ripple Rock was a dangerous navigational hazard in Seymour Narrows, the narrowest passage in the channel that separates Vancouver Island from the mainland of British Columbia.

Seymour Narrows remains a dangerous passage, because during high and low tides, the current through the passage is 28 kilometres per hour (17 mph). Most of the narrows is deep. However, prior to their destruction, in 1958, two rock spikes came very close to the surface. Ships that sailed near the rocks were at risk due to the powerful whirlpools the tidal currents caused. The taller of the two rocks rose to within 3 metres (9.8 ft) of the surface, during low tide -- shallow enough to tear up a ship's hull.