Abstract Since the 12th century AD land reclamation is carried out in The Netherlands. Numerous shallow, salt or freshwater lakes were pumped dry, changing the lakes into polders. These persistent pumping activities have caused substantial land subsidence in the areas surrounding these polders. In order to assess the impact of pumping water out of a planned new polder (Markerwaard) on the adjacent land areas, a large multidisciplinary study has been performed. In this paper the geological, geotechnical, geohydrological, environmental and constructional aspects of this planned land reclamation project will be discussed. Furthermore, attention will be paid to potential measures for mitigating the harmful effects of land reclamation. It will be demonstrated that it was impossible to make reliable cost calculations of the potential damage to housing, infrastructure, crops and environment due to the construction of the polder, without proper knowledge of the geological conditions of the area and its wide surroundings.