Heiðmörk was proclaimed a municipal conservation area of Reykjavík in 1950. It is located southeast of Elliðavatn, Iceland, and is about 6 miles from the city of Reykjavík. Its name is derived from its namesake in Norway, Hedmark, an area with deep forests.The total area of the conservation area is 3,200 hectares. It is a popular recreational area in Iceland. Heiðmörk is where Reykjavík's water reservoirs and drinking water wells are located.
Rauðhólar are a notable natural formation of Heiðmörk, a cluster of red coloured pseudocraters.
Wikipedia https://en.wikipedia.org/wiki/Heiðmörk
Coordinates 64°4'0.127" N -21°46'51.723" E