Heidesee, Nature reserve in Coesfeld, Germany.

Heidesee is a 5.2-hectare nature reserve southeast of Coesfeld, centred on a shallow heath pond formed in a hollow of wind-blown sand left by the last ice age. The pond is ringed by swamp forest and open heath, with bog plants such as bog cotton, cranberry and round-leaved sundew at its edges.

The hollow that holds the Heidesee is thought to be a deflated cover sand surface left by the last ice age. From the second half of the 19th century the surrounding Coesfelder Heide became increasingly overgrown with scrub, so only a sparse remnant of open heath survived around the pond. The 5.2-hectare area is now fenced and protected as a nature reserve.

The reserve draws nature enthusiasts who come to observe moorland habitats and heathland ecosystems firsthand. Visitors can watch how the landscape shifts through the seasons and observe the animals that depend on this environment.

Wear sturdy footwear since the ground can be muddy and waterlogged depending on the season. Stay on marked paths and keep respectful distance from wildlife to avoid disturbing the habitat.

The reserve is a known spawning site for the endangered moor frog, which breeds in the shallow pond each spring. Antlion larvae dig funnel-shaped pits in the sandy ground, and the bog hawker dragonfly is regularly seen around the water.