This presentation will provide an overview of the regional geotechnical and geophysical site investigation studies that have recently been carried out across New Zealand, with a focus on improving our understanding of sedimentary basin structures and the shear wave velocity of regional soil deposits. The field testing methodologies that have been used across these studies will be discussed and how they were applied in each region of interest. Outputs have been used to inform appropriate site subsoil classifications across these regions according to NZS1170.5, with examples of these updated classifications presented and discussed. Methods that have been developed for the rapid characterisation of basins to develop first order velocity models that will inform ground motion simulation efforts will also be summarised. These studies have been supported by a range of different research programmes and in partnership with a number of councils. The presentation will end with a summary of future studies and the need for industry data to improve our understanding of soil profile characteristics across the GeoNet strong motion station network, as part of the update of the New Zealand National Seismic Hazard Model.