Photo: Bjoertvedt·CC BY-SA 3.0· Wikimedia Commons
Islands / Frogn / Bergholmen
An islet just southwest of Håøya, bought for military use as part of Oscarsborg and made the mine fort for Drøbaksundet, the Drøbak narrows. Open to the public today, and a former officers' quarters is let as a coastal trail cabin (*kystledhytte*).
A small islet with only the narrow Kloasundet between it and Håøya. From here the armed forces controlled the sea mines out in Drøbaksundet. Bergholmen was the command post for the minefield barring the way to Oslo.
Part of Kystled Oslofjorden. See all the coastal trail cabins.
Private boat or kayak; coastal trail cabin through Kystled Oslofjorden.
No scheduled boat comes here. You will have to find the nearest public quay yourself, and the rest is your own boat or a kayak. Check the wind and wave forecast before you set out. The open stretches in the outer fjord turn unpleasant in a fresh breeze.
Bergholmen covers around 90 dekar (a dekar is 1,000 square metres), southwest of Håøya and divided from it by Kloasundet. The armed forces bought the islet in connection with the build-up of Oscarsborg fortress. It became the seat of the mine defence of Drøbaksundet, the place from which the sea mines laid in the approach were to be controlled and fired at enemy ships.
The islet belonged to the same barrier system as the guns and the torpedo battery on Kaholmane. Oscarsborg was the visible weapon, the minefield the hidden one.
Bergholmen is open to the public. The old officers' quarters has been fitted out as a coastal trail cabin, let through Kystled Oslofjorden.
Your own boat or a kayak. The coastal trail cabin in the old officers' quarters is booked through Kystled Oslofjorden, run by Oslofjordens Friluftsråd; book ahead, since it is let by the season. The islet is otherwise open for access.
Bergholmen was the brain of the mine barrier. The guns at Oscarsborg took the credit, while the minefield lay ready for whatever they missed.
The officers' quarters where the commanders lived is now a cabin anyone can rent for a night.
Oslo Sea Experience passes Bergholmen on its private fjord trips from Tjuvholmen.
The Norwegian version notes which facts were taken from each source: Bergholmen på norsk.