| Arresø | |
|---|---|
| Location | Hovedstaden region |
| Primary inflows | Pøleå |
| Primary outflows | Arresø Canal |
| Catchment area | 216.1 km² |
| Basin countries | Denmark |
| Surface area | 39.87 km² (15.39 sq mi) |
| Average depth | 3.1 m |
| Max. depth | 5.6 m |
| Surface elevation | 4 m |
| Settlements | Ølsted, Frederiksværk |
Arresø is a lake located at , in the Hovedstaden region just north of Ølsted and east of Frederiksværk on the island of Zealand in Denmark.
At 39.87 km² (15.39 sq mi) Arresø is Denmark's largest lake, based on area. The lake runs into Roskilde Fjord through the Arresø Canal in Frederiksværk. The canal was begun in about 1717 by royal command, and the work was carried out by Danish soldiers and Swedish POW's.
There are a number of rivers and streams running into the Arresø of which the Pøleå is the most significant. Especially along the lake's west side there are a number of hills and ridges. Among these is Maglehøj in the Frederiksværk and Arrenakke Hills, which offers a magnificent view over the lake. East of the town of Frederiksværk is the Arrenæs peninsula which juts out into the lake.
Historically the lake was a fjord, connected to the Kattegat, but the land to the northwest rose after the last Ice Age locking the waters in and creating the lake.
The lake has a rich bird and floral life. Several wildlife preserves have been set up around the lake.
There is a boat tour available on the lake aboard the M/S Frederikke, a renovated, wooden ship. Tours are available during July-August, and start at Arresødal.