Femöre battery (also known as "Battery OD") is a facility previously operated by the coastal artillery arm of Swedish armed forces. It is located only a short trip south-east of Oxelösund on the Swedish east coast, and is blasted into the rock on the Femöre peninsula. The facility totals approx. 3300m² in size, and is connected via an over 450 meter long tunnel, stretching across the length of the facility.