With around 3.3 km² and a depth of 53 m, Laacher See is the largest lake in Rhineland-Palatinate. The area around the lake has been a nature reserve for almost 80 years. The last eruption of the former “Laacher volcano” occurred around 10,930 BC. B.C., about 13,000 years ago. Traces of volcanic activity can still be found in the form of volcanic outgassing, the so-called mofettes, on the eastern shore of the lake. The total ejection quantity of the outbreak at that time was about 16 km³. The eruption was one and a half times as strong as that of Pinatubo in 1991, or 6 times as strong as the eruption of Mount St. Helens in 1980. Although Laacher See is widely regarded as the largest maar in the Vulkaneifel, it is scientifically not a maar and also not a real crater lake, but a water-filled caldera - a burglary crater that resulted from a collapse after the magma chamber was emptied below the volcanic cone. The volcanic mountain collapses and only the ring bead on the outer edge remains. Over time, the remaining boiler fills up with water. The Laacher See is in the Eifel, next to the neighboring Wehrer Kessel, the largest caldera and the only water-filled one in Central Europe.