News of the forthcoming announcement was first reported by the Washington Post after White House officials confirmed the sanctuary plans in a phone interview. The sanctuary is expected to be finalized before the end of the year.
The plans would expand the amount of ocean protected as part of the Pacific Remote Islands Marine National Monument -- first created by President George W. Bush -- from some 87,000 square miles to nearly 782,000 square miles. The single move would double the area of protected ocean in the world.
The Pacific Remote Islands Marine National Monument includes several small islands and atolls, as well as vast ocean to the south and west of Hawaii. The area is home to a diverse array of corals, fish, shellfish, marine mammals, seabirds and other wildlife.
"It's the closest thing I've seen to the pristine ocean," said Enric Sala, a National Geographic explorer-in-residence who's been studying the preserve's biological treasures for nearly a decade.
"These tiny, remote Pacific islands and atolls were some of the last places on the planet to feel the weight of human feet," said Michael Conathan, ahead of Tuesday's announcement. Conathan is the Director of Ocean Policy at the Center for American Progress.
"Today's bold action by the President will minimize the future impact of the footprint of human activity on some of the world's most pristine and resilient ocean ecosystems," Conathan added.