Most whirlpools aren't cause for concern. However, those that are very large or powerful can pose a serious threat to anyone who comes too close. These very strong whirlpools are called maelstroms. They're most likely to form when currents collide near narrow bodies of water, such as straits.

A whirlpool is generally classified as a natural phenomenon or hazard, but it is rarely categorized as a "natural disaster" on its own. A natural disaster is defined by the harmful impact on a human community, and while whirlpools (or "maelstroms") can be dangerous to small watercraft, they do not typically cause the large-scale loss of life or property damage associated with hurricanes, earthquakes, or floods. Powerful whirlpools like Saltstraumen in Norway or the Moskstraumen are predictable tidal events caused by opposing currents and underwater topography. However, whirlpools can be the result of a disaster; for instance, the 1980 Lake Peigneur disaster created a temporary, man-made whirlpool that swallowed barges and trees after an accidental drilling into a salt mine. In that specific context, the resulting vortex was part of a major engineering disaster.