undersea tunnel

Fehmarnbelt - The world's longest undersea tunnel
Denmark and Germany will soon be connected by an 18km underwater tunnel. The project is expected to be completed in 2029.
China installs world's longest undersea steel-casing concrete pipe tunnel
China installed the final section of a 6,845-meter-long undersea tunnel in the Greater Bay Area of Guangdong Province on June 11.
China's $6.7 billion cross-sea bridge mega project sets world record for paving in just one day
China just set a world record while building a sea bridge connecting two cities. What is it?
China completes the world's longest undersea tunnel
The 6.7km undersea tunnel section of the sea crossing bridge connecting Hong Kong, Zhuhai and Macao completed July 7, setting the longest and deepest record in the world, according
China built the world's longest sea tunnel
The tunnel construction project under Bohai Bay connecting Dalian port city in Liaoning province and Yantai city in Shandong province was launched in 1994.