Mineral mining in deep-sea hydrothermal settings will lead to the formation of plumes of fine-grained, chemically reactive, suspended matter. Understanding how natural hydrothermal plumes evolve as they disperse from their source, and how they affect their surrounding environment, may help in characterising the behaviour of the diluted part of mining plumes. The natural plume provided a heterogeneous, geochemically enriched habitat conducive to the development of a distinct microbial ecology.