The industrialization of the oceans is bringing with it a new suite of unregulated noise sources. A formula for quieter seas is looking increasingly remote (see Nature 568, 158–161; 2019).

For example, ever-deeper petroleum operations need seafloor equipment to separate hydrocarbons from brine, gas, sand and mud before piping them to the surface. Multiphase pumps then inject these unwanted substances back into the deposit at extremely high pressures. Such industrial submarine equipment is typically controlled by acoustical communication networks that often operate in the 10–85-kilohertz range. This overlaps with the biosonar range of toothed whales, the hearing range of pinnipeds, such as seals and walruses, and the upper hearing range of baleen whales.

In preparation for the ocean industrial age, NATO has developed JANUS, an underwater acoustical communications protocol. And the US Defense Advanced Research Projects Agency is developing POSYDON, an underwater acoustical global-positioning system. As these technologies advance, high-frequency control and navigation signals could become the most pervasive anthropogenic noises in the sea.