🌬️ Lummelunda Cave

The Lummelunda Cave is located in a nature reserve at Lummelunda north of Visby on Gotland, Sweden. The explored part of this karst cave is almost 4.5 km (2.8 mi), 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.