Hammerknuden or just "Hammeren" is a giant piece of granite bedrock that forms the north western tip of Bornholm.
It rises to 82 meters above sea leve at the highest point at the lighthouse Hammer Fyr (in Danish).
Hammerknuden was formed by glaciers during the ice age. The glaciers moved in from north east to south west and wore down the rocks resulting in a gently rising coastline with skerries to the north and east. To the west where the rock was sheltered from the moving ice only the sea have eroded the rocks. Here the granite rises steeply and provides a good nesting area for numerous sea birds. In many places the rock surface still show the scars from glacial abrasion in the form of long lines.
Where the soil is thin above the bedrock and water is sparse you will see rocky heath with heather, crowberries, juniper and common broom. In other places mixed forest, wet heath and lush valleys can be found. These varied habitats in such a limited area results in a great variety of plant and animal species.
Human activity have marked Hammeren through centuries. The most visible signs of this are the ruins of the church Salomons Kapel (in Danish) as well as the two lighthouses and several quarries.
Hammerknuden is separated from the rest of Bornholm by a rift valley. Bornholms largest lake Hammersø (in Danish) is situated in the bottom of this valley.
There are numerous footpaths on Hammeren. One popular hike follows the marked path along the coast and back via Hammersø.