Remote coral atolls in the Caribbean. Habitat for threatened sharks and rays around a Tanzanian island in the Indian Ocean. And 900,000 square kilometers of the Pacific Ocean around French Polynesia.

These are some of the millions of acres of water now set aside as part of an international goal to protect 30 percent of the ocean by 2030. More than 20 new marine protected areas were announced at the third United Nations Ocean Conference, which ended on Friday in France.

Countries and territories pledging new areas included Chile; Colombia; French Polynesia; Portugal; Samoa; Sao Tome and Principe; the Solomon Islands; Tanzania; and Vanuatu.

“Protecting the ocean is beginning to become fashionable,” said Sylvia Earle, a marine biologist and oceanographer who served as chief scientist of the National Oceanic and Atmospheric Administration in the 1990s, at an event celebrating a network of protected areas around the Azores.

The new designations come at a time when the United States, which sent only two observers to the conference, has moved to reopen the Pacific Islands Heritage Marine National Monument to commercial fishing. The country is also seeking to unilaterally authorize mining of the seafloor in international waters.

France, which hosted the conference with Costa Rica, pushed for a moratorium on deep sea mining, with four new countries pledging their support this week, bringing the total to 37 countries.