7 Famous Underwater Tunnels — Now India to Join With Brahmaputra Project

India is set to build its first underwater road tunnel after the Centre approved a major infrastructure project in Assam. The Cabinet Committee on Economic Affairs (CCEA), chaired by Prime Minister Narendra Modi, cleared the proposal for a four-lane access-controlled greenfield corridor connecting Gohpur and Numaligarh in Assam. This approval marks a historic milestone for India’s infrastructure, placing the country among the few in the world to build a road-cum-rail tunnel under a major river, while connecting strategic regions and drastically improving travel efficiency. (AI Generated)

The project comes with a total capital cost of Rs 18,662.02 crore. At the heart of the corridor will be a 15.79-kilometre-long road-cum-rail tunnel beneath the Brahmaputra River, which will be India’s first and the second of its kind globally, according to a press release by the CCEA. This tunnel is expected to strengthen strategic security and drastically reduce travel times, cutting hours of journey into just minutes. Now, India’s upcoming tunnel joins the ranks of some of the world’s most remarkable underwater tunnel projects. (AI Generated)

Seikan Tunnel, Japan – The world’s longest underwater railway tunnel, spanning 53.85 kilometres, with 23 km under the sea (Tsugaru Strait). It connects Japan’s Honshu and Hokkaido islands and sits 240 meters below sea level, supporting even bullet trains.

Channel Tunnel (Euro Tunnel), UK-France – Connecting England and France under the English Channel, the 50.45 km tunnel has 37.9 km underwater, making it the world’s longest underwater section. Completed in 1994, it is vital for Europe’s trade and tourism.

Tokyo Bay Aqua-Line, Japan – A unique bridge-and-tunnel combination spanning 15.1 km, including a 9.6 km underwater tunnel (Aqua Tunnel) connecting Kawasaki and Kisarazu. In the middle, an artificial island called Umihotaru serves as a rest area and tourist attraction.

Marmaray Tunnel, Turkey – One of the deepest immersed tube tunnels, it passes under Istanbul’s Bosphorus Strait, connecting Asia and Europe by rail at a depth of 60 meters below sea level. Completed in 2013, it is designed to be earthquake-resistant.

Ryfast Tunnel, Norway – The world’s deepest underwater road tunnel, stretching 14.3 km and reaching 292 meters below sea level, connects Stavanger to the Ryfylke district. It eliminates the need for ferries across Norway’s challenging fjord geography.

Hong Kong-Zhuhai-Macau Bridge Tunnel, China – Part of the world’s longest bridge-cum-tunnel system (55 km), it includes a 6.7 km underwater tunnel located between artificial islands, allowing ships to pass. The tunnel significantly reduces travel time between Hong Kong, Macau, and Zhuhai.

Eurasia Tunnel, Turkey – Built under Istanbul’s Bosphorus, this 14.6 km tunnel is designed for cars and light vehicles, with a two-level underwater section of 5.4 km located 106 meters below sea level. Opened in 2016, it eases traffic between Asia and Europe.