What is the height of channel tunnel?

The Channel Tunnel, also known as the Chunnel, is a 50.5-kilometre (31.4-mile) undersea rail tunnel that connects Folkestone, Kent, in the United Kingdom, with Coquelles, Pas-de-Calais, near Calais, in northern France, beneath the English Channel at the Strait of Dover. It is, therefore, the longest undersea rail tunnel in the world.