Why China is so keen to salvage shipwrecks in the South China Sea

Deep under the South China Sea, below the reach of sunlight, lies treasure. Last year Chinese researchers found two rotting shipwrecks some 1,500 metres down and 20km apart. One contains thousands of porcelain cups and vases, their bright blue-and-white glazes half-covered in silt. The other holds timber. The two wrecks offer a glimpse of global trade during the Ming Dynasty (1368-1644), when porcelain fired in the imperial kilns of southern China was shipped to buyers as far away as Europe. The timber was probably headed in the other direction, perhaps towards Chinese shipyards. The discoveries are of interest, however, not just to scholars.