WASHINGTON -- President George W. Bush on Tuesday defended his record on the environment as he designated three parts of the Pacific Ocean as the world's largest marine protected areas.

The trio of "marine national monuments" span a total of 195,280 square miles (505,000 sq km) and include the Mariana Trench and northern Mariana Islands, the Rose Atoll in American Samoa and a chain of remote islands in the Central Pacific.

"The monuments will prohibit resource destruction or extraction, waste dumping, and commercial fishing," Bush said.

"For seabirds and marine life, they will be sanctuaries to grow and thrive. For scientists, they will be places to extend the frontiers of discovery," he said.

Active volcanoes along the seabed, the Earth's deepest point, hydrothermal vents and boiling sulfur pools are among the underwater curiosities that are protected under the Marianas Trench Marine National Monument.

Coral reefs abound and rare species such as whales, sea turtles and Hawaiian monk seals inhabit the areas included in the Pacific Remote Islands National Monument, which includes seven areas including Wake Island, the site of a World War II battle of Japanese and US forces.

Finally, the Rose Atoll Marine National Monument will be named around a small but dense coral reef known for its pink shade at Rose Atoll, a remote area around American Samoa.

Bush, an avid fisherman who leaves office this month to make way for president-elect Barack Obama, defended his administration against critics who say he has fallen short on environmental interests.

"The new steps I've announced today are the capstone of an eight-year commitment to strong environmental protection and conservation," Bush said, touting his efforts to stem air pollution, raise fuel efficiency standards for vehicles and invest in alternative energy sources.

"And while there's a lot more work to be done, we have done our part to leave behind a cleaner and healthier and better world for those who follow us on this Earth," Bush said.