When he leaves the Oval Office this month, he will have safeguarded more of the ocean than any other president, and increased the amount of protected waters around the U.S. by 20 times. His administration has also worked to improve American fisheries, clamp down on illegal fishing, and create national policies for protecting the oceans. Such measures are vital at a time when the oceans are imperiled by many threats.

BEIJING — More than 140 years ago, the United States government designated Yellowstone as the nation’s first national park — an untouched Western landscape of geysers, grizzly bears and soaring peaks. The national parks program eventually expanded to include more than 450 sites and has become one of the country’s greatest tourist draws.