With the stroke of a pen, U.S. President Barack Obama has created the largest sanctuary for ocean life in the world. The Papahānaumokuākea Marine National Monument was created by President George Bush in 2006 and according to the White House, includes "the Northwestern Hawaiian Islands Coral Reef Ecosystem Reserve, the Midway Atoll National Wildlife Refuge, the Battle of Midway National Memorial, and the Hawaiian Islands National Wildlife Refuge." The Monument was already huge, encompassing 362,000 square kilometers of uninhabited land and sea northwest of the big islands that make up most of the state of Hawaii. In the proclamation released today, President Obama nearly quadrupled the amount of protected land to 1.5-million square kilometers, extending the boundaries of the monument, which prohibits fishing or commercial exploitation in an area of 320 kilometers in all directions. The White House describes the region as rich in biodiversity, home to "more than 7,000 marine species, of which approximately one quarter are unique to the Hawaiian Islands." The region was also chosen for its historic significance. It is home to a number of sunken U.S. and Japanese planes and ships, including the aircraft carrier USS Yorktown, which was sunk during the Battle of Midway in World War II, and is now submerged in nearly 5,000 meters of water. "All told," the White House said, the "area serves as a final resting place for the more than 3,000 people lost during the battle." In a statement supporting the decision, the environmental group Greenpeace said that sanctuaries like the one Obama created today "have proven to be powerful tools to ensure the health of our oceans." They also urged more expansion of coastal areas in order to help fish stocks rebound. Not everyone in the region was in favor of the monument's expansion. A number of Hawaii's state legislators sent the president a letter in May opposing the move, saying it would hurt Hawaii's fishing industry. The latest of many The expansion of Papahanaumokuakea followed Thursday's declaration of a 35,000 hectare area of land in Maine known as the Katahdin Woods and Waters National Monument. Both designations coincided with the 100th anniversary of the establishment of the National Park Service. The White House said this "protected area — together with the neighboring Baxter State Park to the west — will ensure that this large landscape remains intact, bolstering the forest’s resilience against the impacts of climate change."