The Etendeka continental flood-basalt province in northern Namibia, linked by the Walvis Ridge to the Tristan da Cunha hotspot, has great importance in global plate tectonic concepts, and is an ideal place to understand the role of the plume-lithosphere interaction during the break-up of the Southern Atlantic Ocean. Within this frame we operated an amphibian passive-source seismic network (WALPASS for Walvis Ridge Passive Source Experiment) in the region where the Walvis Ridge intersects with the continental margin of northern Namibia. The land network operated for over two years while the OBS stations were in operation for one year. The broadband seismic network is composed of 28 three-component land stations and 12 ocean-bottom stations. This configuration of stations will allow us to map the lithospheric and upper mantle structure in the ocean-continent transition beneath the passive continental margin of northern Namibia and to examine possible seismic anomalies related to the postulated hotspot track from the continent to the ocean along the Walvis Ridge. The acquired data should help clarify the velocity anomaly in the lowermost mantle caused by the Africa super plume and to improve the distribution of seismicity in this geophysically little studied region.