President Bush is to create the world’s largest marine protection area in the Pacific Ocean.

Mining and commercial fishing will be banned across 195,000 square miles (505,000 sq km) that includes three “marine monuments”: the Mariana Trench, the deepest on the planet, Rose Atoll in American Samoa and seven islands strung along the Equator in the central Pacific.

The three zones are the habitat of hundreds of species of bird and fish that are not found elsewhere, including the world’s largest land crab and the rare Malaysian megapode, a bird that incubates its eggs in the heat of underwater volcanoes.

They also contain rare geological formations: the Mariana Trench sinks to a depth of 36,000 feet (11,000 metres) below sea level — 6.8 miles. It is five times as deep as the Grand Canyon and deeper than Everest is tall. Rose Atoll, the smallest atoll in the world with only 20 acres (8 hectares) of land, is home to 85ft trees and is a vital nesting ground for the endangered green sea turtle and hawksbill sea turtle.

“These locations are truly among the last pristine areas in the marine environment on Earth,” said James Connaughton, chairman of the White House Council on Environmental Quality. He said that they would “benefit future generations through enhanced science and knowledge”.

The creation of the protection zones will be seen by many as an attempt by President Bush to secure an environmental legacy. His Administration has been heavily criticised for its reluctance to cut carbon emissions, its granting of permission to drill for oil in formerly protected offshore areas of Alaska and its moves to weaken endangered species legislation.

Environmentalists welcomed the decision although some said that the monuments could be protected more effectively. Critics pointed out that the Marianas zone extended only 50 miles from the islands, not the 200 miles that they had lobbied for, and that only the waters between the ocean floor and the rim of the Mariana Trench would be off limits, leaving fishermen free to work the upper reaches. The US military will also continue to operate in all three areas.

The zones’ geological and ecological conditions have created some of nature’s rarest phenomena. The Mariana Islands Monument will include rare mud volcanoes that contain what are thought to be some of the most ancient lifeforms on Earth in a boiling pool of liquid sulphur. The only other one known to exist is on Io, one of Jupiter’s moons. The Rose Atoll Marine National Monument will protect a coral reef area known for rare birds such as petrels, as well as reef sharks and bumphead parrot fish.

Agnes McPhetres, former president of the Northern Mariana College, said: “We’re not going to stop now. Once \ Obama gets in we’re going to keep pushing. We need these waters to be fully protected.”

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