India’s First Undersea Tunnel in Mumbai Set to Open by November 2023. The Mumbai Coastal Road Project is nearing completion and is set to significantly improve transportation infrastructure in the city.

• At a cost of Rs 12,721 crore, the project features a 2.07-kilometre twin tunnel under the Arabian Sea, Girgaon Chowpatty, and Malabar Hill, which will be India's first.
• The tunnels have a diameter of 12.19 meters and will be located 17-20 meters below sea level.
• The project required 35 men and a massive Chinese Tunnel Boring Machine (TBM) to cut through complex geological strata for over two years. The tunnels will open to the public by November 2023.