Saltstraumen is a sound with a strong tidal current located some 30 km east of the city of Bodø, Norway. It is the strongest tidal current in the world. Up to 400 million m³ of seawater forces its way through a 3 km long and 150 m wide strait every six hours, with water speeds reaching 20 knots. Vortices up to 10 m in diameter and 5 m in depth are formed when the current is at its strongest; this feature is commonly known as a whirlpool.
