"For seabirds and marine life, they will be sanctuaries to grow and thrive," Mr. Bush said.
Nearly 200,000 square miles are covered: The Mariana Trench near Guam and waters surrounding a string of islands far south and west of Hawaii. And Rose Atoll, an Island east of Samoa.
The area is home to colorful deep-water fish, sharks, whales and dolphins.
The Mariana Trench is deeper than Mount Everest is tall, with gasses from the earth's core bubbling through. And the only bird known to incubate its eggs with heat from a volcano.
Mr. Bush had already set aside 140 square miles of Hawaiian Ocean in 2006.
"Long after this president is gone and after many of the edicts of his presidency are long forgotten, these places and the life they contain will still be there," said Josh Reichart of the Pew Environmental Group.
And so as George Bush leaves office, the president many environmentalists loathe will have protected more ocean than any other person in history.