We present a novel passive seismic investigation targeting a potential geothermal resource in the Tasmanian Midlands. This study leverages ambient noise tomography (ANT), a technique that extracts Earth's subsurface velocity structure from background seismic noise. We focus on a 53 km x 27 km region centered on Lemont, aiming to develop a 3D tomographic model of seismic wave speeds to a depth of 3 km. A dense network of 144 portable seismometers was deployed for four weeks, and the data was processed using a Hierarchical Bayesian approach to retrieve 3D seismic wave speed variations. Our tomographic inversion reveals a low-velocity zone co-incident with low subsurface resistivity derived from Magnetotellurics, potentially indicative of a geothermal resource.