A gas hydrate sink of 430 square kilometers, the largest of its kind in the world, has been discovered. The discovery was made by a China-German joint expedition over the northern continental slopes of China South Sea, aboard a scientific survey ship named SUN. During the expedition, scientists found massive carbonate reefs in the continental slopes east of the Dongsha Islands, with a depth ranging from 550-650m to 750-800m. Sea floor video and samples collected show the existence of massive natural carbonate growths in pipe, chimney, bread ring, plate, and cake shapes. They are either lying standalone on the sea floor, or protruding from sediments, with Bivalves dotted among them. Gigantic carbonate reefs erect on the sea floor, looking quite similar to the ??chemical reefs?¯ found at the rims of Costa Rica and external seas of Oregon, though much larger than the latter in size.