High Quality Content by WIKIPEDIA articles! The Channel Tunnel (French: Le tunnel sous la Manche; also referred to as the Chunnel) is a 50.5-kilometre (31.4 mi) undersea rail tunnel linking 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. At its lowest point, it is 75 metres (250 ft) deep. At 37.9 kilometres (23.5 mi), the Channel Tunnel possesses the longest undersea portion of any tunnel in the world, although the Seikan Tunnel in Japan is both longer overall at 53.85 kilometres (33.46 mi), and deeper at 240 metres (790 ft) below sea level.