Underground hydrogen storage is anticipated to play a crucial role in balancing fluctuations in renewable energy supply and demand, while ensuring a steady supply of hydrogen for the manufacture of hydrogen fuel derivatives and products like green iron. Among the various options for hydrogen storage, salt (halite) caverns are preferred given their large scale, stability, comparatively low cost, and high rates of injection and withdrawal. As part of Resourcing Australia’s Prosperity initiative, Geoscience Australia is investigating the suitability of different salt accumulations across Australia for underground hydrogen storage, including offshore regions. Two offshore basins appear to be potentially suitable: the offshore Polda Basin (west of the Eyre Peninsula, South Australia) and offshore Petrel Sub-basin (south west of Darwin, Northern Territory). Both basins are proximal to key planned hydrogen production and export hubs and appear to contain thick accumulations of rock salt, confirmed by borehole, geophysical and mineralogical (x-ray diffraction) analysis. Alternative onshore salt cavern options are approximately 1000 km away. It is uncertain how close to shore potentially suitable salt extends for both basins and this is the subject of ongoing work at Geoscience Australia. Experience of salt cavern construction in northern Germany for gas storage (onshore, but close to the coast) demonstrates that seawater can be used for solution mining and the brine disposed of via ocean outfalls. The solution mining process takes several years. Currently, there is uncertainty on whether the Protocol Convention on the Prevention of Marine Pollution by Dumping of Wastes and Other Matter 1972 (the "London Convention") prevents hydrogen storage offshore. Geoscience Australia’s mapping of Australia’s offshore salt resources provides a foundation for decision-making on any potential future amendments to the Convention and advancement of hydrogen storage in Australia.