The Fehmarn Belt Fixed Link: A tunnel connecting Denmark and Germany that will have a section that runs underwater
The Istanbul Metro: A metro system under construction in Istanbul, Turkey that will include an underwater section.
The Thessaloniki Metro: A metro system under construction in Thessaloniki, Greece that will include an underwater section.
The Crossrail Project: A train line under construction in London, England that includes a tunnel section under the River Thames
The Hong Kong-Zhuhai-Macau Bridge: A bridge-tunnel system connecting Hong Kong, Macau, and Zhuhai in China.
The Melbourne Metro Tunnel: A tunnel under construction in Melbourne, Australia that will include an underwater section.
The Mumbai Trans Harbour Link: A bridge-tunnel system under construction in Mumbai, India that will include an underwater section.
The Helsinki-Tallinn Tunnel: A proposed tunnel connecting Helsinki, Finland and Tallinn, Estonia that would include an underwater section.