The Terrifying Undersea Tunnels Completed or Planned

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Most people are familiar with the Channel Tunnel (or "Chunnel") that links the U.K. and France. But around the world, other undersea tunnels are in use or proposed to shorten transportation times. We've listed the longest ones for you, along with a list of some of the most serious new tunnel proposals. Would you be brave enough to travel under the ocean in one of these feats of engineering?

24/7 Wall St. Insights

• The longest undersea tunnel in the world links Japan's two largest islands.
• One of the most interesting proposed tunnels is a link between Spain and Morocco under the Strait of Gibraltar.
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7. North Cape Tunnel

Entrance to the North Cape Tunnel.

• Location: Norway
• Date completed: 1999
• Length: 4.3 miles
• Facts: Connects the North Cape region to the Norwegian mainland.

6. Qingdao Jiaozhou Bay Tunnel

This is the Qingdao Jiaozhou Bay Bridge, which opened the same day as the nearby tunnel.

• Location: Shandong Province, China, running beneath Jiaozhou Bay.
• Date completed: 2011
• Length: 4.8 miles
• Facts: A second tunnel is currently being built. It will be 9.87 miles long and have 6 lanes in each direction.

5. Great Belt Bridge Tunnel

The Great Belt Fixed Link includes this bridge segment.

• Location: Connects the islands of Zealand and Funen, Denmark.
• Date completed: 1998
• Length: 4.98 miles with an additional two bridges making a total length for the link between thing islands of 11 miles.
• Facts: The second longest bored tunnel in Europe, with 31 connecting tunnels.

4. Tokyo Bay Aqua-Line

Mt. Fuji in the background of a bridge that is part of the Tokyo Bay Aqua Line.

• Location: Links Kawasaki and Kisarazu across Tokyo Bay, Japan.
• Date completed: 1997
• Length: 5.9 miles in two separate tunnels linking artificial islands.
• Facts: A road and rail line.

3. Ryfast Tunnel

Road construction in Stavanger, part of the Ryfast Tunnel project.

• Location: Norway
• Date completed: 2020
• Length: 8.9 miles in a system of two tunnels.
• Facts: The deepest subsea road tunnel, reaching 958 feet at the deepest point.

2. Channel Tunnel (Chunnel)

A car in a rail transport going through the Channel Tunnel.

• Location: Links the United Kingdom and France
• Date completed: 1994
• Length: 31.35 miles
• Facts: A rail link that carries more than 10 million passengers a year.

1. Seikan Tunnel

Entrance to the Seikan Tunnel.

• Location: Links Honshu and Hokkaido islands, Japan
• Date completed: 1988
• Length: 33.46 miles
• Facts: The world's longest undersea rail tunnel.

Proposed Tunnels

The Strait of Gibraltar is the strategic entrance to the Mediterranean Sea and the closest point between Africa and Europe.

These are some of the most serious proposals for new long-distance undersea tunnels:

• Strait of Gibraltar Tunnel: a 9-mile link between Spain and Morocco. Construction is to begin in 2030.
• Suðuroyartunnilin: a 16-mile link between two of the Faroe Islands planned for 2030.
• Strait of Sicily Tunnel: a 96-mile connection between Sicily and Tunisia. Under preliminary study.

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