Underwater train systems, also known as underwater railways, are not as uncommon as you might think, here are some examples of underwater train systems around the world.
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1
The Channel Tunnel connects the United Kingdom and France via a 50.45-kilometre rail tunnel beneath the English Channel.
Image Source - Wikipedia
2
The Seikan Tunnel is not entirely underwater but includes a 23.3-kilometre underwater section, it connects the islands of Honshu & Hokkaido.
Image Source - Wikipedia
3
This is a combination of bridge and tunnel system in Japan, connecting the city of Kawasaki in Kanagawa Prefecture with the city of Kisarazu.
Image Source - Wikipedia
4
This undersea tunnel is currently in the proposal stage, If built, it would connect Helsinki, Finland with Tallinn, Estonia.
Image Source - Wikipedia
5
This underwater tunnel is planned to connect Dalian and Yantai in China, Construction is expected to begin soon.
Image Source - Wikipedia
6
The Fehmarn Belt Fixed Link will connect Fehmarn, Germany with Lolland, Denmark, it will feature a rail tunnel beneath the Fehmarn Belt.
Image Source - Wikipedia
7
This high-speed rail line will include a 7-kilometre underwater section when completed.
Image Source - Wikipedia
8
Kolkata boasts India's first underwater metro route, Inaugurated in 2024, a portion of the line runs beneath the Hooghly River.
Image Source - Wikipedia