President Barack Obama, who’s already protected more public acres than any U.S. president, will add to his legacy of conservation by quadrupling the marine monument surrounding the remote Northwestern Hawaiian Islands, the White House announced.

The designation, expected to take effect Friday, will expand Papahānaumokuākea Marine National Monument from 139,797 square miles to 582,578 square miles, making it the largest marine protected area on the planet.

The White House said the move “provides critical protections for more than 7,000 marine species,” including federally protected monk seals, whales and sea turtles, as well as black coral ― the longest-living marine species in the world.

The expansion also is expected to make the area more resilient to climate change-related threats, including rising sea levels, warming ocean temperatures and acidification.

Sen. Brian Schatz (D-Hawaii), who introduced the proposal in June, called Obama’s move “one of the most important actions an American president has ever taken for the health of the oceans.”

“Expanding Papahānaumokuākea will replenish stocks of ‘ahi, promote biodiversity, fight climate change, and give a greater voice to Native Hawaiians in managing this resource,” Schatz said Friday in a statement. “This declaration sets us on a strong path forward for our irreplaceable environment and the generations to come.”