Riemke, Nature reserve in Hemer, Germany.

Riemke is a nature reserve in Hemer covering an area of wetland with shallow water zones and reed beds. The landscape contains sections of open grassland and wooded areas that support different forms of wildlife.

The pond was the settling basin of the lime-processing works at Oberrödinghausen, run by the Rheinisch-Westfälische Kalkwerke (now Rheinkalk); its use ended around 1970. In 1989 the Märkischer Kreis first protected it as a nature reserve under the name Ehemaliger Klärteich von Riemke, and in 2015 it was redesignated simply as Riemke.

Since 1988 the Arbeitskreis Heimische Orchideen Nordrhein-Westfalen has mown the pioneer woodland and cleared shrubs there. The orchid Epipactis palustris was planted in that year and now numbers over a thousand specimens; before the planting there was no occurrence anywhere in the Märkischer Kreis.

The site is best explored on foot with paths around the water zones. Wear sturdy footwear and stay on marked routes to avoid disturbing the habitat and its inhabitants.

Rare orchid species flourish in the wetland areas, including varieties that have become scarce elsewhere. The site attracts specialized bird species that depend on reed habitats for breeding.