Hike around lake Båntjern

Båntjern is a mountain lake in Oslo forest named Nordmarka. It is situated south of Vettakollen, a hill close to one of Oslo's suburbs. It offers various facilities including, swimming, a place for grilling, camping and a diving tower.
A trail walk continues further west of Båntjern. It leads to the top of Vettakollen, an area with views over the Oslofjord and the Bunnefjord.