Best Undersea

The Seikan Tunnel is a 53.85-kilometre railway tunnel located in Japan, connecting the main island of Honshu with the northern island of Hokkaido. Spanning beneath the Tsugaru Strait, it was officially opened in 1988 to provide a reliable transportation link unaffected by harsh maritime weather. The...

The Marmaray Tunnel is a 76-kilometer commuter rail and metro corridor in Istanbul, Turkey, of which roughly 13.4 kilometers run beneath the Bosphorus strait through a submerged tube tunnel. The underwater section connects the European and Asian sides of the city, making it the first rail link betwe...

The Øresund Tunnel is an immersed tube rail and road tunnel located beneath the Øresund strait, connecting Copenhagen, Denmark, to the artificial island of Peberholm. Completed in 1999 and opened to traffic in 2000, it serves as the westernmost underwater segment of the Øresund Bridge-Tunnel fixed l...

The Tokyo Bay Aqua-Line is an expressway in Japan that spans Tokyo Bay, connecting the cities of Kawasaki in Kanagawa Prefecture and Kisarazu in Chiba Prefecture. Opened in 1997, the 15-kilometer route consists of a 9.6-kilometer undersea immersed tube tunnel and a 4.4-kilometer bridge. It is design...

The Great Belt East Tunnel is a twin-bore railway tunnel beneath the eastern channel of Denmark's Great Belt strait. Opened to rail traffic in 1997, it runs for roughly eight kilometers between Zealand and the island of Sprogø and forms the railway portion of the Great Belt Fixed Link. It carries el...

Stingray Marina is a marionette character featured in the 1960s British television series *The Adventures of Stingray*. She represents a pioneering use of “supermarionation,” bringing an undersea heroine to life through intricate puppet animation. Marina’s silent role and Pacifica origins made her a...

A road tunnel opened in 2016 beneath the Bosphorus Strait in Istanbul, Turkey, connecting Europe and Asia and reaching approximately 106 meters below sea level, making it one of the deepest road tunnels in the world.

The Queensway Tunnel, also known as the Birkenhead Tunnel, is a major road crossing beneath the River Mersey connecting Liverpool to Birkenhead in England. Officially opened by King George V in 1934, it was the longest underwater road tunnel in the world at the time of its completion. The tunnel mea...

The Busan-Geoje Fixed Link is a major transportation infrastructure project in South Korea that connects the metropolis of Busan to neighboring Geoje Island across the Geoje Strait. Opened to traffic in 2010, the route combines cable-stayed bridges with deep immersed-tube tunnels to allow continuous...

The Cross-Harbour Tunnel is Hong Kong's first underwater road tunnel, connecting Hung Hom in Kowloon to Causeway Bay on Hong Kong Island. Opened in 1972 after four years of construction, this immersed tube tunnel runs beneath Victoria Harbour and forms a critical part of Route 1 in Hong Kong's road...

The Shin-Kanmon Tunnel is an undersea railway tunnel beneath the Kanmon Strait, linking Honshu and Kyushu in Japan. Opened in 1975 as part of the Sanyo Shinkansen, it carries high-speed trains between Shimonoseki in Yamaguchi Prefecture and Kitakyushu in Fukuoka Prefecture. It provides the Shinkanse...

The Mont Blanc Tunnel is a major trans-Alpine road tunnel linking Chamonix in France with Courmayeur in Italy. Opened in 1965, the structure stretches for 11.6 kilometers (7.2 miles) directly beneath the Mont Blanc massif in the Alps. It serves as a crucial transportation corridor for commercial fre...

The Shanghai Yangtze River Tunnel is a large subterranean crossing located in Shanghai, China. Opened to traffic in 2009, it forms a crucial segment of the expressway linking the Pudong New Area to Chongming Island. The structure utilizes a combination of immersed tube and massive shield-bored secti...

The Qingdao Jiaozhou Bay Tunnel is a major undersea road tunnel located in Shandong province, China. Opened in 2011, the infrastructure spans approximately 7.8 kilometers beneath Jiaozhou Bay, directly connecting Qingdao's primary urban core with the Huangdao district. It was engineered to accommoda...

The Westerscheldetunnel is a 6.6-kilometer immersed tube road tunnel in Zeeland, Netherlands, opened in 2003. It runs beneath the Western Scheldt estuary, providing a crucial road link connecting the region of Zeeuws-Vlaanderen to the rest of the Netherlands on the N62 route. Before its construction...

The Eastern Harbour Crossing is a combined road and rail tunnel situated beneath Victoria Harbour in Hong Kong. Inaugurated in 1989, it became the territory's third cross-harbour crossing, linking Quarry Bay on Hong Kong Island with Kowloon Bay. The infrastructure accommodates both vehicular traffic...

King Titan is a villainous marionette character from the 1964 British science-fiction television series "Stingray," created by Gerry and Sylvia Anderson. As the ruthless tyrant of the underwater city of Titanica, he operates as the primary antagonist to the World Aquanaut Security Patrol (WASP). He...

Phones is a marionette character from the 1964 British science fiction television series Stingray, produced by AP Films and created by Gerry and Sylvia Anderson. Using the trademark Supermarionation puppetry technique, the show followed the adventures of the World Aquanaut Security Patrol. The chara...

The Marina Coastal Expressway Tunnel is a key component of Singapore's underground expressway network and represents the country's first below-sea-level road tunnel. Opened in 2013, the 5-kilometer Marina Coastal Expressway runs partly beneath the seabed to link the eastern and western road networks...

The Kingsway Tunnel, also known as the Wallasey Tunnel, is a major undersea road infrastructure project connecting the city of Liverpool to Wallasey beneath the River Mersey in England. Opened in 1971, it was constructed to alleviate heavy traffic congestion on the older Queensway Tunnel, which had...

The Wuhan Yangtze River Tunnel is an underwater passage running beneath the Yangtze River in Wuhan, Hubei Province, China. Opened in 2008, it holds the distinction of being the first road tunnel to cross the Yangtze River. The tunnel extends for approximately 3.63 kilometers, connecting the city's m...

The Western Harbour Crossing is a major dual three-lane immersed-tube road tunnel situated beneath Victoria Harbour in Hong Kong. Opened in 1997, the tunnel serves as a critical infrastructure link connecting the West Kowloon reclamation area to Kennedy Town on Hong Kong Island. It operates as a tol...

The Nanjing Yangtze River Tunnel is a major road infrastructure project spanning about 6.04 kilometers beneath the Yangtze River in Nanjing, Jiangsu Province, China. Opened in 2010, the twin-tube crossing was constructed to alleviate severe traffic congestion on the city's existing bridge network. I...

Hess Tablemount is a flat-topped submarine volcano in the Pacific Ocean, named after geologist Harry Hammond Hess, who first defined and classified guyots in 1946.

The Great St. Bernard Tunnel is an alpine road tunnel that facilitates vehicular transit between Bourg-Saint-Pierre in the Swiss canton of Valais and Saint-Rhémy-en-Bosses in Italy's Aosta Valley. Spanning a distance of approximately 5.7 kilometers, it bypasses the historic Great St Bernard Pass, pr...

A road tunnel in Miami, Florida, opened in 2014 connecting the Port of Miami to the MacArthur Causeway to divert freight truck traffic away from downtown surface streets.

Pigafetta Guyot is a flat-topped Pacific seamount named after Antonio Pigafetta, the Italian chronicler who meticulously documented Ferdinand Magellan's historic 16th-century circumnavigation.

Fieberling Tablemount is a flat-topped submarine volcano in the Pacific Ocean, notable for its distinct geological formation and the complex ecosystems it hosts.

Thomas Washington Guyot is a Pacific Ocean seamount named after the renowned American oceanographer and Scripps Institution director.