A surge channel is a narrow inlet on a rocky shoreline. As waves strike the shore, water fills the channel, and drains out again as the waves retreat. The narrow confines of the channel create powerful currents that reverse themselves rapidly as the water level rises and falls.

Surge channels can range from a few inches across to 10 feet or more. They may create tide pools if the conditions are correct, but the rapid water movement almost always creates a dangerous situation for people or animals that are caught in it. The West Coast Trail

West Coast Trail

The West Coast Trail is a long backpacking trail following the southwestern edge of Vancouver Island in British Columbia, Canada. It was built in 1907 to facilitate the rescue of survivors of shipwrecks along the coast, part of the treacherous Graveyard of the Pacific...

 on the coast of Vancouver Island

Vancouver Island

Vancouver Island is a large island in British Columbia, Canada. It is one of several North American locations named after George Vancouver, the British Royal Navy officer who explored the Pacific Northwest coast of North America between 1791 and 1794...

, B.C., is famous for its large number of surge channels, some of which are impassable even at low tide and must be crossed inland.