This paper considers large scale erosion of late medieval peatland landscapes along the tidal lagoon of the northeastern Zuyder Zee area (today: Noordoostpolder, The Netherlands). This time period, known for its dynamic history of coeval loss of peaty coastal plains and boom of maritime activities, is studied from archaeological, geological and historical data perspectives. In the first half of the Middle Ages (500-1000 AD), vast peatlands and interconnected lakes characterized the study area. During the Late Middle Ages (1000-1500 AD), increased stormsurges and tidal incursions allowed for extensive progressive erosion of inhabited peatlands, transforming the central Netherlands into the Zuyder Zee tidal lagoon. The study area is the northeastern quadrant of this lagoon. Medieval terrestrial geological and archaeological records from that area have fallen prey to erosion, reworking and uptake into lagoon bottom deposits. Due to these major disturbance factors, a late medieval palaeogeographical reconstruction of the region has not yet been made. However, surveyed since the 1940ies, especially the archaeological data shows spatial clustering that resolves the pacing of lagoon expansion. High-density areas of late medieval archaeological objects represent submerged leftovers of former settlements. The object-clusters are key to resolving what parts of land were transformed in what types of lagoon waters and when. Hence, in mapping the lost terrestrial landscape for medieval stages we flipped the order of input-disciplines: archaeology was put first and geology second, while for earlier periods or other regions the opposite order is the convenient choice. The paper is divided in four major integrated themes: the palaeography of the study area, spatial archaeohistorical research, incorporation and critical analyses of earlier reconstructions and the formation of a regional palaeogeographical reconstruction visualized in a map series. These maps honor the late medieval maritime archaeological evidence and comply ...