Countries trying to claim continental sea floors is not new. It has been becoming more common though. Better technology allows use to explore and exploit vast natural resources that were once unknown and inaccessible. A recent surge in continental sea floor claims has just concluded because of the ten year deadline set by the Convention on the Law of the Sea.
Countries must prove their claim by showing how it is connected via continental shelf if they wish to be granted sole access to the resources below. Some countries like France, Spain, and the United Kingdom have filed joint claims and will share resource access. Others like Russia and the other Arctic countries will continue to bicker over the North Pole. Some old disputes are about to be reborn: Argentina has claimed the sea surrounding the Falkland Islands. Last time that argument got hot a war broke out.
The United States has not rush to claim any additional continental sea floor because it has not ratified the treaty.