Phytoplankton in the ocean supply half of the oxygen in Earth’s atmosphere. Iron supply limits the growth of phytoplankton in the Southern Ocean as well as elsewhere in the global ocean. Situated entirely within the anemic Southern Ocean, Australia’s only active volcanoes, Heard and McDonald islands on the Kerguelen Plateau, are among the world’s most active hotspot volcanoes. Existing data show extensive blooms of phytoplankton on the Plateau and the existence of fields of submarine volcanoes, some of which appear to be active, extending for several hundred kilometers away from the islands. Data and samples acquired during RV Investigator voyage IN2016_V01 in January/February 2016 are testing the hypothesis that hydrothermal activity driven by active submarine volcanoes in the Heard and McDonald islands region fertilises surface waters with iron, thereby enhancing biological productivity beginning with phytoplankton.