China's first undersea tunnel connecting the southeastern Fujian province with Xiamen island was opened to traffic on Monday.
The Xiamen island is one of the special economic zones launched by the government in the 1980s, Xinhua reported.
The 8.7-km tunnel, built at a cost of 3.2 billion yuan ($468 million), was designed for driving speed of about 80 km per hour and is expected to cut travel time between the two areas from an hour to just nine minutes.
It took four years and eight months to complete the tunnel. Six kilometres of the tunnel is under the sea with a maximum depth of 70 meters. It boasts the world's largest tunnel with a maximum area of 170 sq. meters.
“The tunnel was designed and constructed by Chinese experts and is a result of extremely tough work caused by loosening soil and a permeable sand layer under the water, said Zeng Chao, vice director of the tunnel project.
"The project garnered valuable experience for building more undersea tunnels in the future," he added. Two more tunnels will be built in Fujian province, and another tunnel is under construction in Jiaozhou Bay in eastern Shandong province, said Zeng.
The government is also planning to build an undersea tunnel between Fujian province and Taiwan.
Chief engineer of the railway ministry He Huawu said close economic ties between China and Taiwan made the building of a cross-Strait undersea tunnel very important.
Volume of cargo between Taiwan and the mainland grew by an average 11 percent annually and the growth rate for the other way was 20 per cent in recent years.
In 2008, both sides launched their first direct cargo flight and shipping services after a gap of sixty years.