Kattegat, or Kattegatt, is a bay of the North Sea and a continuation of Skagerrak, bounded by Denmark and Sweden. The Baltic Sea drains into the Kattegat through Öresund and the Danish Straits.

Waterways that drain into the Kattegat are the rivers of Göta älv at Gothenburg, together with Lagan, Nissan, Ätran and Viskan from the province of Hallandia on the Swedish side, and the river of Gudenå from Jutland, in Denmark.

The main islands of the Kattegat are Samsø, Læsø and Anholt, where the latter two, due to their dry summer climate, are referred to as the Danish desert belt.

The name Kattegat derives from the Dutch and low Saxon words Kat (cat) and Gat (hole). It refers to the medieval navigation, where captains spoke of this area to be as narrow as a cat's hole, since there are several flats in the sea, which made navigation difficult.

See also: Scandinavia