"The Grandmother beach" - only suitable for the toughest grandmothers! (for those who like to climb up and down the rocks to reach the water. But the little sandy beach there will make it easier for everyone)
Pick rasberries and blueberries for snack!
The beach is located 1,5 km before you arrive to Ingjerstrand in Oppegård, south for Oslo. Take bus 87.
More info here (norwegian)