A cross-border approach to exploration, appraisal and development is important in mature areas, such as the Atlantic Margin, and in frontier areas, such as the Barents Sea. An approach of this nature emphasizes the need to see the basin as one geological entity to maximize economic recovery and prepare the area for the energy transition. This volume offers an up-to-date, ‘geology-without-borders’ view of the stratigraphy, sedimentology and tectonics trends in these areas. It also looks at the challenges associated with differences in data continuity and nomenclature across median lines. A companion volume (SP494), Cross-Border Themes in Petroleum Geology I: The North Sea, provides a similar cross-border analysis for the North Sea Basin across the offshore boundaries of Germany, the Netherlands, Norway and the UK. Cross-Border Themes in Petroleum Geology II: Atlantic Margin and Barents Sea will be a valuable reference for every geoscientist working in the Atlantic Margin and the Barents Sea for years to come.