Straits and seaways are fundamental connectors of oceans, seas and more rarely lakes. They areubiquitous in the modern geography and should be common in ancient landscapes. We compare their charac-teristics to improve our understanding of these features, with the aim to define better their geological use.We review geomorphological, oceanographic, geological and depositional characteristics based on well-doc-umented modern and ancient examples, with a stronger focus on the rock record.‘Strait’and‘seaway’are differentiated by their spatial and temporal scale. This influences the type and per-sistence of oceanographic circulation and sediment distribution. Straits are individual depositional systems,with predictable bedform and facies changes along the sediment transport pathway, whereas seaways are largerand longer-lived physiographic domains, composed of numerous depositional systems. Therefore, their strati-graphic signature in the rock record should be significantly different. We conclude that straits and seaways areend members of a continuum, giving rise to the occurrence of intermediate cases with transitional characteris-tics. The distinctive geological usage of the terms‘strait’and‘seaway’, even without sharp boundaries betweenend members, may be helpful for predicting their occurrence, stratigraphy, palaeogeography, biota distributionand potential distribution of reservoirs and seals for fossil resources and CO2storage
