Priority 1: The area includes significant lochs and river systems, and wetland in the form of upland peat bogs. While much subsequently altered (see Environment priorities), the importance of rivers and lochs for transportation, communication and trade, and the full nature of crannog settlement, remains largely unknown.
Priority 2: The Tay estuary includes an extensive and unexplored intertidal zone, which in the past was fringed with coastal wetlands in the form of estuarine saltmarsh on the Carse of Gowrie and the head of the estuary. While the importance of both the estuary and its main tributary rivers for transportation, communication, and trade has been established since at least the Bronze Age (Strachan 2010), the full extent of use of these environments in the Iron Age, has not been fully realised.