Gulf of Corryvreckan Whirlpool
September 27, 2012
Photographer: Jurgen Rendtel; Jurgen's Web site
Summary Author: Jurgen Rendtel
Off the west coast of Scotland strong tidal flows between the islands Jura and Scarba of the Inner Hebrides Islands, plus an unusual underwater topography, produce the strongest natural whirlpool in Britain. Flooding water moving through the Sound of Jura is squeezed as the Sound narrows. On a full spring tide, this water rushes through the Gulf of Corryvreckan at 8.5 knots (10 mph or 16 km/h).
There's a huge hole (approximately 720 ft or 220 m deep) in the bottom of the gulf’s eastern end. This is followed by a sharp rise to an underwater basalt pillar called "The Old Hag" off the Scarba shore. At the steep eastern face of the Old Hag, water is thrust upwards to the surface in pulses. These "bubbles" are then swept westward by the tidal flow and dissipate into vortices (whirlpools). Furthermore, sizeable waves form and move against the direction of the tidal flow. The three photos above were taken from a small boat during very calm conditions on July 20, 2012 -- about one day after the new Moon. They show from top to bottom the up-thrust, the whirlpool and an impressive wave moving against the tide.
When strong winds are encountered, particularly from the west, wave height is amplified. With prolonged gales and during some storms, standing waves of nearly 10 ft (3 m) have been reported. At these times, it's possible to hear the roar of the Corryvreckan from several miles away.