Hammersø
Hammersø (English: Hammer Lake), or Hammer Sø, is the largest lake on the island of Bornholm and the only tarn in Denmark. It is located in a valley in Hammeren, the northernmost point of the island. A narrow isthmus separates the lake from Opalsø, an artificial lake formed in a granite quarry which was closed in 1970.
The lake is about 650 m long and 150 n wide, covering an area of 10.3 ha, and reaches a maximum depth of 13 m. Its encatchment area is approximately 133 ha, consisting of about 50% rocks, 25% forest and 25% cultivated land.
Coordinates: 55°16′58″N 14°45′54″E / 55.28278°N 14.76500°E
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