LISPWAL Passive continental margins offer the unique opportunity to study the processes involved in continentalextension and break up and the role of hot-spot related magmatism. We propose combined on- and offshore seismic experiments designed to characterize the Southern African passive margin at the location of the Walvis Ridge , to assess the interaction of the presumed plume with continental lithosphere and to determine the deep structure of the transition from the coastal fold belt to the stable craton, where the Walvis Ridge hits the African continent. The project integrates three experiments, (A) an onshore, coast-parallel refraction seismic profile, (B) two onshore-offshore wide-angle seismic transects, and (C) a combined on- and offshore seismic imaging of the sub-Moho velocity (Pn tomography) at the ocean-continent transition. The knowledge of the lithospheric structure of the margin together with results from other geoscientific studies (e.g., conducted within the SPP-SAMPLE) will help to address fundamental questions such as, how continental crust and plume head interact, what the extent and volumes of magmatic underplating is, and how and which inherited (continental) structures might have been involved and utilized in the break up process. With this proposal we apply for funds to conduct the onshore/offshore part of this amphibious experiment, consumables and travel costs for part of the offshore experiment, and the personnel to analyse the amphibian data sets.