This whirlpool effect is caused by the squeezing of the tide though the narrow Gulf of Corryvreckan between Jura and Scarba, over humps and holes in the reef, including a rock pinnacle that rises to 29m from the surface of the sea. This was taken from a small boat that sailed from Easdale.

a documentary team once equipped a mannequin with a life jacket and a depth gauge, and then tossed it into the CorryvreckanWhen it was eventually found, the depth gauge had a maximum reading of over 650 feet. The mannequin was also severely damaged, showing signs that it had been forcefully dragged along the ocean floor.