How are maelstroms formed?

Answer 1

A maelstrom is formed when very strong tides coming from different (opposing) directions meet. This conjunction of strong and opposing tides causes an uncommonly powerful whirlpool - a maelstrom. The most powerful whirlpools are created in narrow, shallow straits, where tidal currents are likely to flow very fast.

The maelstrom has taken its name from the celebrated whirlpool just off the north-west coast of Norway. It is created by the Moskenstraumen, a powerful tidal current in the Lofoten Islands.

Wherever liquids and gases flow quickly past fixed objects eddies or whirlpools may occur. A short-lived but extremely large and powerful maelstrom may be created by a tsunami.

In complete contrast, a small and gentle whirlpool may be seen where water is draining from a sink. The cause of this is not tidal; it is caused by the Earth's rotation. Because the same direction of rotation applies to both the northern and southern hemispheres (i.e. to the whole globe) the water will appear to observers in the two different hemispheres to be whirling down the drain in different directions (clockwise in the north; counter-clockwise in the south). That is because, while the observers are looking at the same rotation, they are viewing it from the opposite directions of north and south.