Both the mouth of the Atran and which sea flow into Kattegat?
Ätran (river) Ätran is a Swedish river. The river is about 240 km long, and has its source in Gullered, Västergötland, at a height of 332 m above sea level. The river has its mouth in Falkenberg, Halland, where the river enters Kattegat.
Nissan (river) Nissan (] ) is a 200 km long river in southwest Sweden. It ends in the Kattegat bay of the North Sea in Halmstad. The straight middle and upper course of Nissan follows an branch of the Protogine Zone —a zone of crustal weakness in western Sweden.