This report is a contribution to the Department of Trade and Industry's (now Department of Energy and Climate Change) Strategic Environmental Assessment SEA2. This review presents a summary of published data and their interpretation from areas in the mature oil and gas areas of the UK North Sea. The basis for this review is the premise that the modern environment is a synthesis of past environmental conditions. The purpose is to review: the evolution of the deeply buried sediments with reference to the petroleum geology and production-related seabed subsidence; the evolution of the shallow seabed sediments with reference to present sediment distributions and seabed features; the evidence for possible hydrogeological exchange across selected onshore/offshore areas; and the history of earthquakes and the hazard that they may pose. It is intended that the review will provide a basis for a better understanding of the impacts of possible future changes in the natural environment.