Oscarsborg Fortress

Oscarsborg Fortress is a coastal fortification on islands in the Oslofjord near Drøbak in Viken county, Norway. It is best known for its role in World War II when its batteries and torpedoes engaged German naval forces.

The site contains preserved coastal gun emplacements and a torpedo battery set into the island rock, together with museum displays covering naval and military history. Visitors can tour gun positions and the torpedo installations, view museum exhibitions and use on-site visitor facilities including a hotel and restaurants.

The fortress evolved over several centuries as a defensive position controlling the Drøbak narrows; its coastal guns and an underwater torpedo battery were active in the early 20th century. On 9 April 1940 the fortress fired on and sank the German cruiser Blücher, an action that delayed the German advance on Oslo and allowed the Norwegian government and royal family to escape.

Located on small islands in the Drøbak Sound roughly south of Oslo, the fortress is reached by ferry from the town of Drøbak and sits at the entrance to the inner Oslofjord.

• Access: Regular ferries and tour boats run from Drøbak during the summer months; timetables vary by season.
• Historic action: The fortress is most visited for its role on 9 April 1940 when coastal batteries and torpedoes delayed the German advance by sinking the heavy cruiser Blücher.

What to See #

• Torpedo battery: A submerged torpedo battery built into the island rock that played a decisive role in 1940 by firing torpedoes at an attacking warship.
• Main gun batteries: Coastal gun batteries that include large-calibre guns preserved on site and visible from the island's promenades.
• Museum and visitor facilities: A museum complex with exhibits on the fortress' military history plus visitor facilities, a hotel and cultural spaces on the island.