Øyeren

Øyeren is a lake in the Glomma River watershed, southeast of the city of Lillestrøm. It is located within the municipalities of Enebakk, Lillestrøm, and Rælingen in Akershus county and Indre Østfold municipality in Østfold county.
Lake Øyeren is the ninth largest lake by area in Norway with a surface area of. It is above sea level and deep.

The name

The name of the lake is derived from øy f 'island; flat and fertile land along a waterside'.

Nordre Øyeren nature preserve

An area that includes parts of the northern end of the lake is an established nature preserve, listed as a Ramsar site.