The Arctic Ocean is melting, and vast untapped oil, gas and mineral stores are opening up. For the past few years Canada and Russia have each been trying to claim the region as their own. Not wanting to walk away empty handed, Denmark has now gotten into the fight, says the Associated Press.

At the crux of the debate over Arctic ownership is a patch of seafloor known as the Lomonosov Ridge, a strip of continental crust that runs along the sea floor just askew from the geographic North Pole.

To make their claims for the North Pole, Russia and Canada, and now Denmark, are trying to prove that the Lomonosov Ridge is an extension of their continental crust—a connection that, under the United Nations Convention of the Law of the Sea, would give them legal claim to the region.

In its case, presented to the United Nations group handling the debate, Denmark is arguing that Greenland is connected to the Lomonosov Ridge. According to the BBC, the new Danish claim would carve huge slices out of Russia and Canada's claims to the Arctic sea floor as well as laying claim to the geopolitical marker of the North Pole itself.