Competing Claims Over Arctic Region

The half-square-mile rock, one-seventh the size of New York's Central Park, is wedged between Canada's Ellesmere Island and Danish-ruled Greenland, and for more than 20 years has been a subject of unusually bitter exchanges between the two NATO allies.

In 1984, Denmark's minister for Greenland affairs, Tom Hoeyem, caused a stir when he flew in on a chartered helicopter, raised a Danish flag on the island, buried a bottle of brandy at the base of the flagpole and left a note saying: "Welcome to the Danish island."

The dispute erupted again two years ago when former Canadian Defense Minister Bill Graham set foot on the rock while Canadian troops hoisted the Maple Leaf flag.

Denmark sent a letter of protest to Ottawa, while Canadians and Danes took out competing Google ads, each proclaiming sovereignty over the rock 680 miles south of the North Pole.

Some Canadians even called for a boycott of Danish pastries.

Canada and the United States dismissed the Russian flag-planting as legally meaningless.

But Russian researchers also plan to use the dive to help map the Lomonosov ridge, a 1,240-mile underwater mountain range that crosses the polar region. Moscow claims the ridge is an extension of the Eurasian continent, and therefore part of Russia's continental shelf under international law.

The U.N. has rejected Moscow's claim, citing a lack of evidence, but Russia is set to resubmit it in 2009. If recognized, the claim would give Russia control of more than 460,000 square miles, representing almost half of the Arctic seabed