Do any trains go underwater?

At present, the Seikan Tunnel is the world's deepest and longest railway tunnel with approximately 23.3km of the tunnel being located under the seabed making it the world's longest undersea tunnel.



Yes, several high-profile railway systems operate deep beneath the sea, utilizing massive tunnels bored through the earth's crust. The most famous is the Channel Tunnel (Chunnel), which carries Eurostar and freight trains between the UK and France; its undersea portion spans 37.9 kilometers, the longest in the world. Japan's Seikan Tunnel is even deeper and longer in total, connecting the islands of Honshu and Hokkaido with a track level roughly 240 meters below sea level. In 2026, other notable underwater rail links include the Marmaray in Istanbul, which crosses the Bosphorus Strait, and various urban subway systems like San Francisco's BART or Hong Kong's MTR that use transbay tubes. Contrary to popular imagination, these are not glass tubes where you can see fish; they are reinforced concrete and steel structures built for safety and speed, often feeling just like a standard dark tunnel to the passengers inside.

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The Seikan Tunnel (Japanese: ??????, Seikan Tonneru or ????, Seikan Zuido) is a 53.85 km (33.46 mi) dual-gauge railway tunnel in Japan, with a 23.3 km (14.5 mi) portion under the seabed of the Tsugaru Strait, which separates Aomori Prefecture on the main Japanese island of Honshu from the northern island of Hokkaido.

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Detroit-Windsor Tunnel It is the third oldest underwater vehicle tunnel in the United States or Canada. It stands behind only New York/New Jersey's Hudson River-crossing Holland Tunnel (completed in 1927) and the Posey Tube (completed in 1928), which connects Alameda and Oakland, California.

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The tubes originate at a junction of two PATH lines on the New Jersey shore and cross eastward under the Hudson River. On the Manhattan side, the tubes run mostly underneath Christopher Street and Sixth Avenue, making four intermediate stops before terminating at 33rd Street station.

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The Laerdal Tunnel in western Norway is the longest road tunnel in the world. It takes about 20 minutes to pass through the tunnel. Brightly colored lights placed every six kilometers help drivers stay alert.

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How Long Are You Underwater on the Eurostar. The speed limit in the Channel Tunnel for trains is 160kph / 100mph. The Channel Tunnel is under the English Channel for 37.9 km or 23.5 miles, which is the worlds longest undersea tunnel. When riding the Eurostar you'll be underwater for about 13 minutes.

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The Chesapeake Bay Bridge: An Underwater Tunnel in Virginia | Chesapeake bay bridge, Places to travel, Beautiful places to travel.

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The Chesapeake Bay Bridge–Tunnel (CBBT, officially the Lucius J. Kellam Jr. Bridge–Tunnel) is a 17.6-mile (28.3 km) bridge–tunnel that crosses the mouth of the Chesapeake Bay between Delmarva and Hampton Roads in the U.S. state of Virginia.

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The Ted Williams Tunnel interface in East Boston between the land-based approach and the underwater section is 90 feet below the surface of Boston Harbor, the deepest such connection in North America.

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Some trains may have composting toilet tanks, which use bacterial action to break down solid and liquid waste. Only the broken down clean liquid is released to the trackbed after sterilisation. The solid waste only has to be emptied every half year.

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