Parts of three remote and uninhabited Pacific island chains, including the Kingman Reef shown here, are being set aside by President George W. Bush as national monuments to protect them from oil and gas extraction and commercial fishing in what will be the largest marine conservation effort in history. (USFWS, Jim Maragos/Associated Press)

The home of a giant land crab, a sunken island ringed by pink-coloured coral, and equatorial waters teeming with sharks and other predators are being designated national marine monuments by President George W. Bush in the largest marine conservation effort in history.

The three areas — totalling some 505,757 square kilometres— include the Mariana Trench and the waters and corals surrounding three uninhabited islands in the Northern Mariana Islands, Rose Atoll in American Samoa and seven islands strung along the equator in the central Pacific Ocean.

Each location harbours unique species and some of the rarest geological formations on Earth, from a bird that incubates its eggs in the heat of underwater volcanoes to a sulphur pool, one of only two known to exist, with the other one found on Jupiter's moon Io.

All will be protected as national monuments — the same status afforded to statues and cultural sites — under the 1906 Antiquities Act. The law allows the government to immediately phase out commercial fishing and other extractive uses.

However, recreational fishing, tourism and scientific research with a federal permit could still occur inside the three areas. The designations will not conflict with U.S. military activities or freedom of navigation, White House officials said.

It will be the second time Bush has used the law to protect marine resources. Two years ago, the president made a huge swath of the Northwestern Hawaiian Islands a national monument, barring fishing, oil and gas extraction and tourism from its waters and coral reefs. At the time, that area was the largest conservation area in the world.

The three areas to be designated Tuesday are larger. The designations came with some opposition and fell short in size and scope of what environmentalists had hoped for. Northern Mariana Islands government officials and indigenous communities initially objected to the monument designation, citing concerns about sovereignty, fishing and mineral exploration.

"These locations are truly among the last pristine areas in the marine environment on Earth," said James Connaughton, chair of the White House Council on Environmental Quality, in a call with reporters Monday. He added that the resources the administration sought to preserve will be fully protected.