The Amundsen Sea embayment of West Antarctica is in a prominent location for a series of tectonic and magmatic events from Paleozoic to Cenozoic times. Seismic, magnetic and gravity data from the embayment and Pine Island Bay (PIB) reveal the crustal thickness and some tectonic features. The Moho is 24-22 km deep on the shelf. NE-SW trending magnetic and gravity anomalies and the thin crust indicate a former rift zone that was active during or in the run-up to breakup between Chatham Rise and West Antarctica before or at 90 Ma. NW-SE trending gravity and magnetic anomalies, following a prolongation of Peacock Sound, indicate the extensional southern boundary to the Bellingshausen Plate which was active between 79 and 61 Ma.An understanding of the glacial history of Pine Island Bay PIB is essential for proposing models on the future development of the West Antarctic Ice Sheet WAIS. Newly collected multichannel seismic reflection data from inner PIB are interpreted in context with already published reconstructions for the retreat history in this area since the Last Glacial Maximum. Differences in the behaviour of the ice sheet are shown to exist for the western and eastern parts of PIB. While a fast ice retreat was made possible in the western part due to basal melting by warm CDW resulting in large melt water streams we see little influence by melt water streams in the eastern part. There, the shallower basement leads to a shallower seafloor and hence possibly prevents a strong inflow of CDW. As a result the ice retreat in that area was much slower.