I could tell my friend was starting to flag, not being used to walking up hills and I didn't dare tell her we needed to do two peaks for Tjøme, so we just went to Grimstadåsen. We parked on the lower side of Grimstadåsen, at the end of a road leading to some houses/ cabins and followed the path up to the top. Not much of a view. 30 minutes max. round trip.