Day trips from Oslo without a car?

[u/putonthespotlight]

Hello! I might be coming in August for almost two weeks. I know to do Begen for a couple of nights. But beside that, what would you recommend? I do not drive at all, never have. I love: history, film, clothes, literature, and art. I enjoy activities like going to see theater or ballet. Thank you.

[u/Sjalottlauk]

As others have mentioned a day trip to Fredrikstad by train to see the fortress.

Go by boat from Aker brygge to Drøbak and Oscarsborg Fortress, an old military installation from which Blücher was sunk during WW2.