Olstappen is a lake in the municipalities of Sør-Fron and Nord-Fron in Oppland county, Norway.The Vinstra River, coming from the southwest, flows into the west side of Olstappen and flows out of Olstappen’s northeast corner, thence east into Gudbrandsdalslågen at the town of Vinstra. The Espa River flows into Olstappen from the south, making it a tributary of the Vinstra. Olstappen lies south of the town of Skåbu.