Tour the fortress that saved a king

Oscarsborg Fortress

Oscarsborg Fortress is just a five-minute ferry ride from Drøbak.

Oscarsborg Fortress straddles two islets strategically situated in the narrowest portion of the Oslofjord, near the cosy seaside town of Drøbak.

It was early on April 9, 1940, when the fortress opened fire on an invading German flotilla (with, ironically, two aging German-made artillery guns), striking the German heavy cruiser, Blücher. As the burning ship  floated past Oscarsborg’s torpedo battery, it was dealt the fatal blow.  The Blücher eventually capsized and sank, with a loss of more than 800 crew members. The action at Oscarsborg Fortress  delayed the German invasion of Oslo, enabling Kong Haakon VII and Crown Prince Olav, along with members of the government, to flee to England and organize resistance to the German occupation of Norway.

In the summer season, Oscarsborg is a great place to visit for young families and everybody with an interest in culture, history and nature. The Museum of Oscarsborg is open and conducts guided tours. The dramatic story of the Battle of Drøbak Sound (where the Blücher was sunk) is a central element.

Among the activities for children is a history safari through the exciting tunnels of Oscarsborg. There is also Coast Goat Commando, an obstacle course, the TV rescue vessel Elias, plus beaches and places to fish for crabs. Children can learn while they play at Oscarsborg.

The courtyard provides a magnificent setting for concerts and cultural events, and not least the operas that are staged here. For an English copy of this year’s performances, please email

Oslofjord map

Oslofjord map

Access and ferries to Oscarsborg Fortress

Oscarsborg is only a five-minute ferry trip away from Drøbak. The ferries sail every day, year-round. For the ferry schedule, please check the Oscarsborg website or call +47 815 51 900. Or contact Drøbak Tourist Information.

Tickets for the ferry can be bought on the quay or on board. The price for a round trip in the summer season is NOK 70 for adults, and NOK 50 for children. There is also a family ticket (two adults and up to three children) at NOK 180.  (In the winter season there are fewer activities at Oscarsborg and the round-trip ferry ticket is NOK 50 and NOK 35, respectively).

From May on, there is also a weekly ferry connection from Aker Brygge in downtown Oslo that goes via Nesodden, and one from Sætre in Hurum.


There is ample free parking at Sundbrygga Quay in Drøbak.

Guest harbor

For visitors arriving by private boat, Oscarsborg Guest Harbor is staffed, and a pleasant place to arrive.


The Drøbak Sound is well positioned for defensive installations. Under King Christian IV, a blockhouse was erected at the Kaholmane Islet in 1643. The fortress installations did not see any action, however, during the wars between Denmark-Norway and Sweden in the 17th and 18th centuries.

During the 1830s, proposals were discussed for the installations that came to be the Oscarsborg Fortress we know today. The first construction phase was completed on  Nov. 20, 1848, and by December 1852 the rest of the cannons were installed in the main fort. The fortress was completed in 1853.

The fortress was named “Oscarsborg” on the occasion of the visit by King Oscar I on Kaholmen on  Aug. 23, 1855. When the installations were completed, Oscarsborg was considered one of the most modern fortresses in Northern Europe, but this recognition was not to last for very long. As early as 1864, Oscarsborg Fortress was seen to be obsolete due to the rapid development of  artillery technology. The original fortifications at Kaholmane were built as a protection against attacks from the sea. However, the fortress was easily circumnavigated, and could be taken from the land side. Consequently, Oscarsborg went through a second round of construction work in the 1890s. A new torpedo battery was completed in  1901.

On April 9, 1940, Oscarsborg Fortress passed its first real test: The fort’s armaments managed to sink the German flagship, Blücher.

National Fortification Heritage

Oscarsborg Fortress is one of 14 fortresses under the management of National Fortification Heritage. The national fortifications no longer have a key role to play in present-day defense strategies compared with situations in the past. Their declining importance as military installations has made it possible to open the fortresses to the  public. The Norwegian Parliament decided in 2002 that these fortresses would be made available for civilian use. The mandate from the government was to open the fortresses to the public and turn them into living and active destinations.

Source: and

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