The Gemünden maar is lined up along a fissure running SE to NW. About 20,000 to 30,000 years ago it errupted.
The fissure which allowed the magma to rise up, breaches numerous Lower Devonian strata. Some are abundant in fossils, such as the Eckfeld layers named after the homonymous maar.

With a water surface of approx. 7 hectares, Gemünden Maar lake is the smallest of the three Daun Maar lakes. At the height of 406m a.s.l., this is the deepest laid Maar lake among the three near Daun. With a depth of 39m one cannot probably see till the waterbed. Though clear, the water does not contain enough nutrients and oxygen to support a wide variety of fish.

Even so, apart from swimming, fishing and boat riding are the most widely practiced free time activities here.

Parking:
There are two parking areas, a little bit on the upper side of Maar lake, for the visitors. When coming from Gemünden over the Maarstraße, there is a smaller Parking area for the visitors of Waldcafe / Restaurant.                                                                  

Elevation: 406 m (AMSL)
Cone diameter: 620 m
Cone depth: 117 m
Lake diameter: 295 m N-S, 319 m W-E
Lake depth: 39 m                                                                                                                                                 Stand:02.04.2020