As you progress through the game you will eventually meet a bird stuck in the ground. This bird is being attacked and gets their eggs stolen. Just follow the guy to the right of the bird and he will eventually be killed by a bear. Behind this bear, on a pile of rocks, there is a raspberry. Take this and make the bear follow you. Now just walk towards where the guy who got killed looked. You will walk over a bridge, find three or four wall paintings, continue over the next bridge and you will reach a camp.
No achievement notification because I already have it.
Thanks to tynderi for mentioning that this is missable. To do this you need a fresh run of the game.