The campaign to protect 30 percent of the world’s oceans by 2030, supported by more than 70 nations, is known mostly for soaring ambition and scant achievement so far. Just 7 percent of the seas are protected and only 2.7 percent are highly protected.

“It is very optimistic to think we’ll reach ‘30 by 30,’” says Patricia Majluf, a Peruvian fisheries scientist who has worked to create a deep-sea protected area off Peru in the face of strong resistance from the fishing industry. Peru has protected less than half a percent of its offshore waters. The proposed Nazca Ridge Marine Protected Area, on an undersea mountain range