Encore - Gulf of Corryvreckan Whirlpool

June 23, 2018

Corryvreckan02 (2)

Today and every Saturday Earth Science Picture of the Day invites you to rediscover favorites from the past. Saturday posts feature an EPOD that was chosen by viewers like you in our monthly Viewers' Choice polls. Join us as we look back at these intriguing and captivating images.

Photographer: Jurgen Rendtel
Summary Author: Jurgen Rendtel

September 2012 Viewer's Choice Off the west coast of Scotland strong tidal flows between the islands of 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.