Project HALO 2022 has started with Australia’s Marine National Facility RV Investigator sailing to the northern Great Barrier Reef with an international science team, to study Halimeda (calcareous green algae) sediment mounds – the largest such bioherms in the world.

Many mysteries remain – why do they exist, their strange ‘donut’ shapes about 300 m across, how long have they existed on the GBR? This voyage will multibeam map, collect cores and biota, deploy cameras and oceanographic sensors to help understand this extensive deep shelf ecosystem.