"It's absolutely one of the most important moves in marine conservation, probably in my lifetime," Academy biologist Healy Hamilton said.
Hamilton knows a lot about the remote pacific - she did some of the research that helped the president make his decision.
Palmyra is a group of tiny islands 1,000 miles south of Hawaii that is just a small part of the ocean territory now protected.
"The area that's been protected is larger than the state of California, so it's a vast expanse of Pacific Ocean," Hamilton said.
The president established three new national monuments - all near U.S.-controlled islands scattered around the Pacific. The areas include the Mariana Trench near Guam, the Rose Atoll near American Samoa and a cluster called the Pacific Remote Islands.
"They are all basically uninhabited, a few of them like Wake Island became famous because of World War II, and the Japanese took over the island for a short period of time, but for the most part hasn't been anybody out there, so the seabird population and the coral reefs and the fishes have all been left there to go about their merry life without any impacts from humans," Lance Morgan of the Marine Conservation Biology Institute said.
The monument designation means there will be no commercial fishing, no oil or gas drilling, no fancy resorts.
The island cluster is one of the few places birds can stop and rest in the middle of the pacific and it is a haven for birds that nest on the ground.
Palmyra is also home to endangered coconut crabs, the world's largest land invertebrates.
Being able to study a pristine habitat like this is critical.
"It's like jumping in a time machine when you jump underwater there," Hamilton said. "We spend a lot of money all around the world trying to protect and restore coral reef eco systems, if we don't understand what they even look like or how they even function in their natural state, we don't have a goal we don't have an end for our efforts.
Even with the new declaration, less than 1 percent of the ocean around the world is protected. But the Marine Conservation Biology Institute says President Bush has still made a great step forward.
"He certainly set a high mark for the oceans by doing this, and hopefully an example for many other nations of the world," Morgan said.
Conservationists point out that protecting large underwater areas actually helps the entire ocean, because many creatures born in the protected areas will swim or fly away and replenish other eco-systems.