HK-Zhuhai-Macao Bridge's underwater tunnel done

An underground tunnel section of the long-awaited Hong Kong-Zhuhai-Macao Bridge was completed on Friday, marking the end of construction of the main structure for the world's longest cross-sea bridge, the bridge management authority said.

The 6.7 kilometer tunnel is 48 meters under the waters of Lingdingyang in the Pearl River Estuary - the longest and deepest underwater tunnel in the world.

The tunnel is comprised of 33 pipe-shaped sections linked by one 6,500-metric-ton butt joint in the middle. Each pipe weighs about 80,000 tons, as much as an aircraft carrier.