Whirlpools

Whirlpools are natural vortices in which water rotates around a central axis. They form when fast-moving currents meet, when water is funneled through constricted passages, or when tides interact with underwater topography such as shelves, sills, or reefs. The spinning column can extend several meters below the surface and may be accompanied by visible whitewater, air entrainment, and surface turbulence.

Formation and mechanics: As water converges in a narrowed channel or around an obstruction, angular momentum concentrates and a vortex develops. Energy supplied by tides, river inflows, or ocean currents maintains the swirl. Friction with the seabed and surface tension dissipate energy, while vertical motions can create downwelling at the core, sometimes pulling objects or swimmers toward the center.

Types and examples: Oceanic whirlpools, sometimes called maelstroms in popular language, vary greatly in size. River whirlpools are usually smaller and form where fast water rounds bends or collides with submerged obstacles. Notable examples include the Gulf of Corryvreckan near Scotland, Moskstraumen and Saltstraumen in Norway, which have attracted attention for their dramatic and persistent whirlpools.

Impact and safety: Whirlpools can pose hazards to navigation, swimmers, and small craft. They influence local mixing, transport nutrients, and create complex three-dimensional flow patterns that are of interest to coastal hydrodynamics and ecology.