The Corryvreckan is a narrow strait between the islands of Jura and Scarba, in Argyll and Bute, on the northern side of the Gulf of Corryvreckan, Scotland. It is the third-largest whirlpool in the world. Flood tides and inflow from the Firth of Lorne to the west can drive the waters of Corryvreckan to waves of more than , and the roar of the resulting maelstrom, which reaches speeds of , can be heard away. Though it was classified initially as non-navigable by the Royal Navy it was later categorized as extremely dangerous.