Öjen old-growth forest is an exceptionally large area that belongs to old-growth forest conservation programme. The area is also protected by Natura 2000 network. The forest is mostly dominated by spruce and is swampy in places.
There is a marked nature trail in Öjen. Along the trail there are information signs with interesting facts about the nature, medicinal plants and folk tales of the area. Öjen is situated close to the centre of Vaasa and is therefore a good destination for day trips.
In Öjen you can find varying habitats from lush groves to barren pinewoods. The oldest trees are nearly 200 years old and many decades have passed since the last logging. Therefore the amount of decayed trees and polypores growing on them has increased greatly.