rotary oceanic current, a large-scale eddy that is produced by the interaction of rising and falling tides. Similar currents that exhibit a central downdraft are termed vortexes and occur where coastal and bottom configurations provide narrow passages of considerable depth. Slightly different is vortex motion in streams; at certain stages of turbulent flow, rotating currents with central updrafts are formed. These are called kolks, or boils, and are readily visible on the surface.

Notable oceanic whirlpools include those of Garofalo (supposedly the Charybdis of ancient legend), along the coast of Calabria in southern Italy, and of Messina, in the strait between Sicily and peninsular Italy. The Maelstrom (from Dutch for “whirling stream”) located near the Lofoten Islands, off the coast of Norway, and whirlpools near the Hebrides and Orkney islands are also well known. A characteristic vortex occurs in the Naruto Strait, which connects the Inland Sea (of Japan) and the Pacific Ocean.