The irregularities in the bottoms of river basins and channels that often cause eddies in rivers and lakes. The intensity of the eddies is changing, for example in the open sea they are giant but without suction, like the Sargasso Sea in the Atlantic Ocean, but in the past they were either retained in the center or they were sent by the rotating winds towards the rocky coasts . On the other hand, eddies with great movement of the vortex can be very violent and are able to sink boats in their fast rotating cavities. Among the notable eddies are the Caribdis in the Strait of Messina, between mainland Italy and the island of Sicily, there is also the Maelstrom on the Lofoten Islands, near Norway, and Whirlpool Rapids under the Niagara Fall.
