There are about 350 volcanoes in the volcano Eifel; of these, 75 are formed as "Maar" and 12 Maare have a Maarsee, including Eichholzmaar. With a diameter of 120 metres and a maximum depth of 3 metres, Eichholzmaar belongs to the smaller Eifelmaar. Nevertheless, the circular shape of the Maarkessel is clearly visible. If rising lava with a temperature of 1200 degrees meets groundwater only a few hundred meters below the surface of the earth, a huge explosion of water vapor occurs. The rock and the rising lava are crushed and ejected, and a funnel is blown into the surface of the earth. Such funnels blown into the earth’s crust by volcanic activity are called “Maare”. The circular shape and the geophysical evidence of a funnel-shaped structure with steeply sloping edges prove that we are here on a Maar that was blasted into the Devonian sandstone tens of thousands of years ago. A 23 m deep core borehole in the Maarboden has produced a sequence of ice age debris and more recent warm age lake deposits. The change from the last cold season to the warm season is also indicated by the change from a birch and pine vegetation to a vegetation dominated by hazelnut, oak and elm. The lake sediments and the Niedermoortorfe in a depth of 6 - 7 meters give a clear indication of permanent water cover or water saturation and air seal, they are about 9,300 years old. The volcanic ash of the nearly 13,000-year-old Laacher Lake eruption, the most devastating volcanic eruption in the Eifel, has been detected at a depth of about 12 metres. The Eichholzmaar is thus a unique archive for the recent climatic and settlement history of the region. The Maarsee was drained at the beginning of the 19th century and used as arable and meadow area. Between summer 2007 and spring 2008, the Eichholzmaar was renatured and the former water surface was restored. Since then, Eichholzmaar has developed into a refuge for rare waterfowl and reptiles. Location: on the road from Steffeln to Duppach from the small parking lot on the country road it is still 300 m to the Maarsee. In the vicinity of the Eichholzmaar there are other volcanic destinations. Visit the volcano garden Steffeln or the Steffelner Drees