The Bullerteich in the northern part of the Warstein district is a special gem. The tranquil pond got its name from the rising bubbles, which indicate the formation of natural carbonic acid in the limestone. Directly opposite is the Trockelsknäppchen spring, which was found during the construction of an air raid shelter in the limestone rock during the Second World War. Today, thanks to the Friends of the Bullerteich Association, it can be viewed through windows.