Nidelva[1] is a river in Trondheim Municipality in Trøndelag county, Norway.

The Nidelva is at its deepest at the Trongfossen, a deep ravine in the village of Klæbu.

The Nea River is a tributary which empties into Selbusjøen, which in turn flows into the Nidelva.

[3][4] The popular Norwegian waltz, Nidelven Stille og Vakker du er ("Nidelven quiet and beautiful you are"), was written by composer Oskar Hoddø (1916–1943).

According to tradition, Hoddø wrote the waltz about the Nidelva River one night in late April 1940 while he was standing at Gamle Bybro in Trondheim.