The Rogaland Arboret, Stavanger
In Sandnes there is Norway's largets Arboret - a huge area with collections of trees, bushes and flowers, all put together as a very attractive and interesting park with many kilometres of paths to walk along. It's beautiful in all season. I remember going there in December and then, after having inhaled all that healthy cold air smelling of dead leaves, coming home to a nice warm portion of the usual Saturday risgröt!
If you enjoy walks and botanical things, then this is the right place for you!