The coastal areas of Southeast Norway underwent dramatic environmental changes throughout the Mesolithic period. Continuous postglacial land uplift/isostatic rebound lead to retreating shorelines turning former seabed into coastal hinterland. While archaeological research lately has focused on the coastal and marine orientation of Mesolithic groups in the region, their interaction with the wooded coastal hinterland is little researched. This article explores shifting human–environment relations connected to these long-term changes. The starting points are nine archaeological sites in the Oslo fjord region, from which the artefact material shows that they were coast based in the earlier Mesolithic. They all have yielded radiocarbon dates from structures, mostly hearths, with later Mesolithic datings. At these later times, the sites had turned into elevated hinterland locations. First, the archaeological context and sample material of these later dates are discussed; on this basis, it is suggested that these later dates, earlier interpreted as impaction of forest fires, indicate the use of elevated hinterland locations in the Mesolithic. Second, this article explores the relevance of the wooded hinterland for the Mesolithic groups of the region, including animated beings, wayfinding practices and the possible function of these hinterland locations as potential practical and cosmological anchor points and strategic points in a communication system. It is argued that the study of the use of the hunter-fisher-gatherers’ interaction with the wooded and rocky coastal hinterland is needed to achieve a holistic understanding of their involvement and socializing with their world.