The peak of Soidinvuori (”Lek Mountain”) rises in Pihtipudas at an area where the flat peatlands of Northern Ostrobothnia transform into the rocky hillsides of Central Finland. Although the highest spot of Soidinvuori at 170 metres above sea level is just outside the protected area, the terrain inside the Soidinvuori reserve is also rugged in many places.

The Soidinsalo reserve was donated to the Finnish Natural Heritage in his will by Mikko Hakanen, a nature lover from Toivakka, a small town some 150 km south of Pihtipudas. The area of the reserve stands at a respectable 74.8 hectares. Soidinsalo was protected during the centenary of Finland in 2017.

The Soidinvuori blockfields characterize the western end of the reserve where groundwater also flows beneath the rocks. From here flushed, on a walk in late October, a western capercaillie, the regional bird of Central Finland.

In the largest part of Soidinsalo grows a dense mixed forest on a more level ground. The forest is still quite young, but it is speckled by old retention pines, dead standing trees and decaying trunks lying on the ground. Several natural springs also enliven the reserve.