Our DISCOL experiment of 1989 was intended to explore some of the environmental impacts of sea-bed mining (see Nature 571, 465–468; 2019). It did not ‘simulate’ industrial mining of the deep sea as you imply, because it did not cause the type and extent of sea-floor disruption and habitat destruction that would be associated with commercial extraction processes. We simply provoked a mechanical disturbance of the sea floor and studied the recolonization and restoration of the disturbed area over a seven-year period.

Until industry has developed a test system for extracting metalliferous nodules from the sea floor, it will not be possible to simulate the actual impacts of mining or to monitor its effects on sediments and communities. It will then take time to do the environmental investigations and evaluations that are required before commercial mining can proceed.