Generating environmental baseline knowledge is a prerequisite for evaluating and predicting the effects of future deep seabed mining on the seafloor and in the water column. Without baselines, we lack the information against which to assess impacts and therefore cannot decide whether or not they pose an acceptable risk to the marine environment. At present, the International Seabed Authority (ISA), which is the international regulator for seabed mining, requires contractors engaged in mineral exploration to establish geological and environmental baselines for their respective contract areas. H...