Fresh groundwater stored in Australian coastal aquifers constitutes an important resource for humans and the natural environment. However, many Australian coastal aquifers are vulnerable to seawater intrusion the landward encroachment of seawater into coastal aquifers. This report is one technical assessment of the National Seawater Intrusion Project, aimed at characterising current and future seawater intrusion vulnerability of Australian coastal aquifers. This report outlines the development of a typological framework to categorise coastal aquifers and assist in their assessment of vulnerability. The report includes a characterisation of the different hydrogeological and climatic settings of Australia's coastal aquifer. Using public and confidential information, simplified cross-sectional conceptual models of case study areas were developed and aquifer parameters were tabulated for 28 case study areas (CSAs). Key hydrogeological characteristics are analysed and tabulated for use in other aspects of the overall vulnerability assessment.