Japan may have found a new way to claim fresh waters for fishing and oil and gas.

Scientists believe they are close to perfecting a process for cultivating coral, which could be used to change the shape of disputed land masses. Even if the method works it would take decades to add significant size to a rock. But it could mean Japan can bulk-up Okinotori Island - its southernmost piece of real estate (the Japanese call it an island; China says it's merely an atoll or a rock) and claim the surrounding 400,000 sq km of "exclusive economic zone" waters, and all the marine resources that it contains. The Maldives and others at risk from rising sea levels will also be interested.