|Surface area||52 km² (Southern Dellen), 82 km² (Northern Dellen)|
|Water volume||1,226 million m³ (Southern), 1,489 million m³ (Northern)|
|Surface elevation||42 m|
Dellen is a lake system in the province of Hälsingland, Sweden. It consists of two lakes, Northern Dellen and Southern Dellen, appreciated among fly-fishermen for their distinct population of brown trout.
Southern Dellen has a surface area of 52 km² and a water volume of 1,226 million m³. Northern Dellen has an area of 82 km² and a water volume of 1,489 million m³.
The two lakes are only united by a short channel, and it is therefore disputed whether they should be counted as one or two lakes. If counted together, it would have a total area of 130 km², making it the 18th largest Swedish lake.
The vaguely circular lake system was formed by an impact crater 89.0 ± 2.7 million years ago, placing the impact in the Upper Cretaceous. The resulting impact crater measures about 19 kilometres in diameter. It has resulted in the area containing the rock Dellenite (a rock intermediate in composition between Rhyolite and Dacite), which has become the provincial rock.
- Le Maître, R.W. (2002). Igneous rocks: a classification and glossary of terms : recommendations of the International Union of Geological Sciences, Subcommission on the Systematics of Igneous Rocks (2 ed.). Cambridge University Press. p. 72. ISBN 978-0-521-66215-4. Retrieved 27 October 2010.
- "Dellen". Earth Impact Database. University of New Brunswick. Retrieved 2009-08-19.
- Dellen Information and map Dellenbygden.nu; in Swedish only