Understanding the scale of deep-sea mining’s effects is paramount to understand their ecosystem consequences. There is no doubt that deep-sea mining will kill organisms and permanently alter habitats (Drazen et al., submitted). Seafloor disturbance studies clearly show that benthic communities don’t fully recover even after several decades (Jones et al., 2017). Further, much of the fauna relies on the nodules themselves (Amon et al., 2016; Vanreusel et al., 2016) which take millions of years to form. These effects over hundreds of meters to a few kilometers may not comprise a substantial ecosystem impact given the scale of abyssal habitats, but effects over hundreds to thousands of kilometers would surely be defined as serious environmental harm (Levin et al., 2016). Thus the spatial and temporal scales of mining impacts will decide policies and decisions about deep-sea mining activities. There is a clear need to use sediment plume models to estimate the scale of mining impacts in the midwater realm.