Siljan Lake
Dalarnas län
Siljan Lake, located in Dalarna county in central Sweden, is the country's seventh largest lake with a surface area of about 293 square kilometers, extending to 354 square kilometers when combined with adjacent lakes Orsasjön and Insjön. The lake reaches a maximum depth of 134 meters and sits 161 meters above sea level. It lies on the southwestern edge of the Siljan Ring, a circular geological formation created by a massive meteorite impact approximately 377 million years ago during the Devonian period. This impact crater, originally about 52 kilometers in diameter, is the largest known in Europe outside Russia and has preserved sedimentary rocks rich in fossils from the Cambrian, Ordovician, and Silurian periods. The surrounding region includes several towns such as Mora, Leksand, Orsa, and Rättvik. Siljan and its environs offer extensive hiking, cycling, and skiing trails, as well as bathing spots, making it a popular outdoor recreation area with a long history of health resorts and outdoor baths. The lake's unique geology and natural beauty attract hundreds of thousands of visitors annually. Notably, the area has been the focus of scientific deep drilling projects searching for natural gas and oil, although these were not commercially successful. The lake also supports diverse fish species, including some rare and ancient ones like the Ice Age horned sculpin. Siljan’s combination of geological importance, natural beauty, and recreational opportunities makes it a unique destination in Sweden.
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Tip: The best time to visit Siljan Lake is during the summer months when the extensive hiking and cycling trails are accessible and bathing spots are inviting. Visitors are advised to explore the Siljansleden hiking trail, which spans 340 kilometers and follows old pasture routes with rest stops and overnight huts. Booking accommodations in nearby towns such as Mora or Rättvik ahead of peak seasons is recommended. While there are no specific ticketed attractions, visitors should check local tourist information for guided tours or events around the lake. Discounts may be available for group bookings or multi-day passes on certain trails. Local radio station Radio Siljan provides up-to-date tourist information year-round, which can be helpful for planning visits.
Interesting facts
- •Siljan Lake is situated within the largest known meteorite impact crater in Europe outside Russia, approximately 52 km in diameter.
- •The lake and its surroundings preserve sedimentary rocks rich in fossils from the Cambrian, Ordovician, and Silurian periods.
- •A deep underwater trench runs along the lake bed, reaching depths over 100 meters in places.
- •The 1980s deep drilling project reached nearly 7,000 meters, making it one of the deepest boreholes in Europe.
- •Rare fish species such as the Ice Age horned sculpin have been found in the deepest parts of Siljan Lake.
History
The Siljan Ring, the geological formation enclosing Siljan Lake, was formed about 377 million years ago during the Devonian period by a massive meteorite impact, originally creating a crater approximately 52 kilometers wide.
Over time, glacial action shaped the lake and its surroundings, including the creation of Österviken bay during the last Ice Age.
The lake's name, first recorded in 1442, derives from an ancient form related to terms meaning 'channel' or 'to swallow,' likely referring to a deep underwater trench in the lake bed.
The area has been inhabited since at least the Iron Age, with archaeological finds such as Viking Age relics on nearby Sollerön island.
In the 1980s, deep drilling projects were undertaken to explore natural gas and oil potential within the fractured granite of the crater, providing valuable scientific insights despite no commercial fuel production.
Place Guide
Siljan Ring Geological FormationDevonian period, ~377 million years ago
A vast circular structure formed by an ancient meteorite impact, the Siljan Ring is the geological foundation of the lake and surrounding landscape, notable for its fossil-rich sedimentary rocks and unique geology.
Siljansleden Hiking Trail
A 340-kilometer network of hiking trails following historic pasture routes around Siljan Lake and its environs, featuring rest stops and overnight huts for extended trekking.
Dalhalla AmphitheatreFormer quarry repurposed in late 20th century
Located near Rättvik in a former quarry within the Siljan area, Dalhalla is an open-air amphitheatre renowned for concerts and cultural events, blending natural beauty with artistic performances.
