Strong Atlantic currents and unusual underwater topography conspire to produce a particularly intense tidal race in the Corryvreckan channel. As the flood tide enters the narrow area between the two islands it speeds up to 8.5 knots (≈16 km/h,≈10 mph), and also meets a variety of seabed features including a deep hole and a rising pinnacle. These features combine to create whirlpools, standing waves and a variety of other surface effects.

The Corryvreckan is the third largest whirlpool in the world, and is on the northern side of the gulf, surrounding a pyramid-shaped basalt pinnacle that rises from depths of 70 m to 29 m at its rounded top. Flood tides and inflow from the Firth of Lorne to the west can drive the waters of Corryvreckan to waves of over 30 feet (9 m), and the roar of the resulting maelstrom can be heard ten miles (16 km) away.

Although not, as is sometimes believed, formally classified by the Admiralty as unnavigable (the Admiralty's West Coast of Scotland Pilot guide to inshore waters calls it "very violent and dangerous" and says "no vessel should then attempt this passage without local knowledge"), the nearby 'Grey Dogs', or 'Little Corryvreckan', are classified as such. Experienced scuba divers explore the waters, described as "potentially the most dangerous dive in Britain".

AND EVEN BETTER, IT’S RIGHT ON OUR DOORSTEP !