Clear water and deep drop-offs are not features known to Northern German diving, but there are some exceptions. One of them is the “See im Berg” or “lake in the mountain” in Messinghausen near Brilon in the Sauerland mountain region between Dortmund, Kassel and Giessen.
Once you reach the small road leading up the hill in the village of Messinghausen, you will wonder where the lake is. Welcomed by some grazing cows, passing a gate—then you will see it: A former rock quarry, about 141 feet / 43 meters deep and 330 feet / 100 meters in diameter, filled with crystal-clear blue water. What looks like an enormous cooking pot is a manmade structure with a path going around and the steep walls continue below the surface. “The cooking pot description is accurate,” says scuba instructor Matze Schneider from the dive center in Bielefeld. On weekends in the summer, there can be over 50 divers with their bubbles boiling on the surface like a giant cooking pot.
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Visibilities in the winter time can easily exceed 100 ft / 30 meters. Once under water, the walls drop sharply to a maximum depth of 130 feet / 40 meters. Divers feel like being in the blue Caribbean sea, the only difference is the water temperature is only 40 degrees F / 4C. The owners of the quarry have installed large training dive platforms at 20ft / 6m - 30ft / 9m and 90ft /28m.
When reaching 130ft / 40m, the visibility is so good you can often see over half of the bottom of the quarry. Divers in the past have sunk multiple items in the quarry, such as large box containers, round concrete tubes and a few small boats. The big prize sunk in the lake is a real German military ship. After departing the deep region, you ascend past some old cars, such as a “Trabant”, the former “Volkswagen” of the German Democratic Republic and a mannequin dressed in a German GDR military outfit.
You gain the most beautiful impression of the mountain lake by diving onto your back and looking up at the surface. On sunny days, a bundle of sunbeams crests the hills, illuminating the entire scene. Because of the fantastic visibility, one can see above water structures on the hillsides, even from a depth of 130 feet / 40 meters. Only heavy rainfalls affect the conditions in the quarry.
Because of the water temperatures, there is hardly any organic material in the lake, so good conditions remain stable even in the warm summer. You can see several carp and sturgeon swimming around in the quarry.
After leaving the water, there is just one obstacle: One has to ascent the steep quarry path to get to the parking area above. The owners offer a compact car to bring the gear down and up, making the trip much easier.
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Once you reach the small road leading up the hill in the village of Messinghausen, you will wonder where the lake is. Welcomed by some grazing cows, passing a gate—then you will see it: A former rock quarry, about 141 feet / 43 meters deep and 330 feet / 100 meters in diameter, filled with crystal-clear blue water. What looks like an enormous cooking pot is a manmade structure with a path going around and the steep walls continue below the surface. “The cooking pot description is accurate,” says scuba instructor Matze Schneider from the dive center in Bielefeld. On weekends in the summer, there can be over 50 divers with their bubbles boiling on the surface like a giant cooking pot. 
