This report presents preliminary results from a seabed mapping and biodiversity survey of Elizabeth and Middleton reefs within Lord Howe Marine Park in 2020. The primary audience are researchers and managers of the Temperate East network of Marine Parks, with the information to support monitoring of the network. Survey activities included seabed mapping by multibeam sonar, sediment sampling and acquisition of seabed imagery by AUV and of fish communities by underwater video. Mapping reveals a complex seafloor at each reef, with mounds, ridges, planes and depressions. In shallow areas (20-50m), these features form habitat for macroalgae, a diversity of hard reef-building corals, soft corals and bacterial mats. Deeper areas (70-110m) were dominated by black corals, algae (rhodoliths), hard corals, sponges and expanses of coarse carbonate sand. Demersal fish were abundant across the lagoon and shallower shelf, including black cod, Tiger sharks and Galapagos sharks.