Gotthard Base Tunnel: This is the world's longest railway tunnel, stretching for 57.1 kilometers (35.5 miles) beneath the Swiss Alps. It connects the Swiss towns of Erstfeld and Bodio and opened for commercial use in December 2016.
Seikan Tunnel: This tunnel is located in Japan and spans a distance of 53.9 kilometers (33.5 miles) beneath the Tsugaru Strait, connecting the islands of Honshu and Hokkaido. It was opened for service in 1988.
Channel Tunnel: Also known as the Euro Tunnel, this is a 50.45-kilometer (31.35-mile) long tunnel that connects Folkestone, Kent in England and Coquelles, Pas-de-Calais in France. It was opened in 1994.
Lötschberg Base Tunnel: This 34.57-kilometer (21.5-mile) long tunnel is located in Switzerland and connects Frutigen, in the Bernese Oberland, with Raron, in the Canton of Valais. It opened for service in 2007.
Guadarrama Tunnel: This 28.4-kilometer (17.6-mile) long tunnel is located in Spain and connects Madrid and Segovia. It was opened in 2007.
Simplon Tunnel: This is a 19.8-kilometer (12.3-mile) long tunnel that connects Brig, Switzerland and Domodossola, Italy. It was opened in 1906 and is one of the oldest tunnels on this list.
Arlberg Tunnel: This tunnel is located in Austria and connects the towns of Langen am Arlberg and St. Anton am Arlberg. It is 10.6 kilometers (6.6 miles) long and was opened in 1884, making it the oldest tunnel on this list.