135ft under water.
Depending on the tunnel (there are three), they are 1.4 - 1.5 miles long.
The longest under ocean tunnel is the Seikan Tonneru. It is an underwater railway tunnel in Japan. It has a 14.5 mile long portion under the sea bed. The track level is 330 feet below the sea bed.
It is a tunnel under the Channel inside which TGV(High Speed train) Eurostar links France to UK from Paris to London. French call it "Le tunnel sous la manche" In English, it is called "The Channel Tunnel"
The tunnel is 50.5 km long (31.4 miles). of which 37.9 km. (23.5 miles) is below the seabed.
The present Cascade Tunnel is 7.79 miles long. The original Cascade Tunnel was 2.63 miles long.
Long Dock Tunnel was created in 1860.
It wasn't named, that is just where and what it is. The Channel Tunnel runs under the English Channel. It is often just called "the Channel" for short, for example in the phrase "cross channel ferry". There have been proposals to build a tunnel under the Channel for more than 100 years. The proposed tunnel was always referred as "the Channel Tunnel" long before it was built. In French it is known as "Tunnel sous la manche", "La manche" is French for the channel.
The Thames Tunnel is 1,300 feet (396 meters) long.
Abraham Lincoln. The Lincoln Tunnel is a 1.5-mile (2.4 km) long tunnel under the Hudson River, connecting Weehawken, New Jersey and Manhattan, New York City
Alas, no. There are several longer. The longest of all, the Paijanne water tunnel in Finland, is a water supply tunnel so probably doesn't count. The Seikan tunnel in Japan carries a narrow-gauge railway and is 33.5 miles long. The Channel tunnel is certainly the longest full-size railway tunnel at 31.3 miles. However, those crafty Swiss are currently at work under the Alps, and the Gotthard Base tunnel (also a standard gauge railway) will be 35.5 miles long, a clear winner.
The Hoosac Tunnel is 4.75 miles in length or 7.64 km long.
The M5 East Tunnel in Syndey is 8.55 km long.