The Economic Times

Deep beneath Chinas seabed, workers just spent 21 days underwater while building the worlds longest undersea high-speed rail tunnel, linking the Zhoushan islands with China's rail network

Workers in China have completed a 21-day operation to replace 104 cutting tools on a giant tunnel boring machine deep beneath the seabed. The 16.18-km Jintang tunnel will connect the Zhoushan islands with Chinas high-speed rail network and become the worlds longest undersea high-speed rail tunnel.