India’s First Underwater Metro Tunnel To Be Operational By 2023: Kolkata

The construction of India’s first underwater tunnel in Kolkata under the Hooghly River for the establishment of metro links between Howrah and Kolkata is underway and will be made fully functional by 2023. "Important Passage work has also been done keeping in mind that if a technical problem arises inside the water tunnel area, passengers can be taken out through the special passage," stated an official.