The main attraction at Oslo Summerpark is the extensive climbing park with rope courses and zip lines. There are varied routes for both adults and children. The park is open from May 18th to October 14th, but the opening hours vary. Entry prices are determined by height.
There are a number of small farms located around Oslo which are perfect for those with small children.
The Kampen Organic Farm for Children (in Norwegian) is a small inner-city farm with animals and activities.
Ekeberg Dyrepark in Ekebergparken has many different animals including goats, sheep, birds, cows, and horses. Entry is 60 NOK and the whole family is free to wander around and pet the animals. There is a picnic area, café, and pedal tractors and other activities for the kids.
Sæteren Gård is an activity farm for children run by DNT. The farm offers several different fun activities for children of all ages. There is a small maze, an obstacle course, animals such as hens and rabbits, fire pits, and a nature trail with trolls and other creatures from Norwegian fairy tales.
If you have a spare day where you want to get out of the city and see something a little different, there are plenty of options. For adventures along the Oslofjord, follow the coast to Ytre Hvaler National Park on the eastern side, or Færder National Park on the western side. Both destinations are easy to reach and offer islands to explore, beaches and pretty hiking trails.
For a taste of the mountains, head to Beitostølen for pack-rafting or a husky cart safari.