Lummelunda Cave

The Lummelunda Cave (, also known as the Rövarkulan, "The Robbers' Den") is located in a nature reserve at Lummelunda north of Visby on Gotland, Sweden. The explored part of this karst cave is almost , making it one of the longest caves in Sweden. It is created by the drainage water from the Martebo mire. The water forms a stream with its outlet in the Baltic Sea. In the 15th to 19th centuries, mills and an ironwork were set up by the stream.