The Kelle is a gypsum cave near Appenrode and lies in the fascinating karst landscape of the Naturpark Südharz (South Harz Nature Park).
The water-soluble gypsum rock has also helped to create natural spectacles such as sinkholes, dolinas, creeks, karst springs, steep gypsum slopes or gypsum caves such as the Kelle. Originally, the Kelle was a giant hall about 85 metres long and filled with water. In the course of time, however, it was leached out and transformed by standing karst water, so that today it only consists of a large sinkhole and a half-open grotto with a small lake.