The land ministry plans to acquire an unmanned submersible craft so it can gather data that will help it search for natural resources in its exclusive economic zone, ministry sources said Saturday.
The ministry intends to request ¥1.1 billion from the 2011 budget to buy the submersible, which would be put into use in fiscal 2012.
Japan has been trying to secure its maritime interests in recent years. To discover and exploit undersea natural resources, detailed data on the undulation of the seabed and the configuration of the crust beneath it is necessary.
The probes that have been conducted using equipment on Japan Coast Guard survey ships are only capable of gathering precise data to a depth about 200 meters.
The submersible being sought would look like a 10-meter-long rocket and would be able to submerge to the depth of about 2.5 km, the sources said. It would be able to take a preprogrammed route and measure terrain from 50 meters above the seabed using sonar.
The Land, Infrastructure, Transport and Tourism Ministry plans to use the submersible in deep waters deemed as promising sites for oil or gas deposits, the sources added.
The EEZ is defined as an area within 200 nautical miles, or about 370 km, from a country's coast. But Japan has found itself tussling with China over maritime interests, including gas exploration in the East China Sea, where their self-proclaimed EEZs overlap.
China also argues that Okinotori Island, an tiny uninhabited coral reef located 1,740 km south of Tokyo that is barely visible at high tide, is not an island but a group of rocks, opposing Japan's claim that its EEZ extends to a continental shelf around its southernmost island.