Jungferweiher, Protected area in Ulmen, Germany

Jungferweiher is a reservoir in the Eifel near Ulmen, formed from a dry maar that has been flooded again since 1942. The lake covers about 23 hectares, is only about 0.8 metres deep and lies at roughly 430 metres above sea level, stretching about 0.9 km north to south and up to 0.3 km across. Its outflow runs into the nearby Ulmener Maar.

Jungferweiher is a dry maar that was flooded again in 1942; its outflow runs into the Ulmener Maar just to the south and from there via the Nollenbach into the Üßbach. The nature reserve covering the northern and eastern parts of the lake and adjoining wet areas was established in 2000 and covers 33 hectares. A bird protection area has existed since 2006 and covers 45 hectares.

The name Jungferweiher, "maiden's pond", is the common German term for a dry maar later flooded again. The lake was refilled in 1942 and drains south into the Ulmener Maar, which then feeds the Nollenbach and the Üßbach. Since 2000 the northern and eastern parts with adjoining wet meadows form a 33-hectare nature reserve.

A flat circular walking path circles the entire lake and can be used by people with reduced mobility and families with young children. Information stations and viewing points are positioned around the route for visitors to observe wildlife and learn about the area.

The lake is a dry maar that was flooded again in 1942; its outflow runs into the Ulmener Maar just to the south and from there via the Nollenbach into the Üßbach. The water level lies at about 430 m above sea level, and the lake is only about 0.8 m deep.