Source-to-sink system analysis involves a complete, earth systems model approach from the ultimate onshore drainage point to the toe of related active deepwater sedimentary systems. Several methods and techniques have evolved in recent years, from experimental and numerical modelling through analysis of modern and recent systems, to analysis of ancient systems. A novel method has been developed, bridging between the previous approaches and dividing and analysing source-to-sink systems based on linked geomorphic segments along the source-to-sink profile. This approach builds on uniformitarian principles. The method is driven by the need to understand ancient, subsurface systems and still has high uncertainty but is an original, first-order approach to source-to-sink system analysis. In modern systems, entire onshore-to-offshore systems can be analysed with a higher degree of confidence than in ancient systems and semi-quantitative relationships can be established. Application in ancient systems is much more challenging but, in some cases, antecedent morphologies have been preserved onshore that can be matched with offshore known occurrences of, for instance, sandy submarine fan systems. Along the Norwegian North Sea and Norwegian Sea margins the Paleocene deep-marine reservoir of the giant Ormen Lange gas field is such an example. There, antecedent onshore drainage patterns which formed the feeder system to the offshore, deepwater fan system can be interpreted and aligned with onshore palaeogeomorphological evidence. Understanding the palaeogeomorphic development of basement regions such as the Fennoscandian shield is of high importance for understanding the offshore presence of deepwater sandstones.