SIYUAN is highly competitive in terms of its underwater tunnel technologies, with the design work volume of underwater tunnels topping the country. SIYUAN has carried out the design and proposal study of 17 underwater tunnels, including Wuhan Yangtze River Highway Tunnel—— “the first tunnel across the great Yangtze River”, Nanjing Yangtze River Tunnel with the largest diameter in the world, Shiziyang Tunnel of the Guangzhou-Shenzhen-Hongkong Railway——the first sea-crossing railway tunnel in China, Hubei Liuyanghe River Tunnel, Hangzhou Qianjing River Tunnel, etc.. SIYUAN is the only design company mastering various functions and methods for underwater tunnel construction.