Answer
England and France (The tunnel connects folkstone in Kent with Coquelles in Fance and Spans a Distance of Just Over 50km the Vast Majority of Which is Under the Sea. The Tunnel Consists of Two Rail Tunnels with a Smaller Service Tunnel in Between. You Cannot Drive a Vehicle Such as a Car Through the Channel Tunnel it Must Be Stored on Board the Rail Shuttle Which Happens to Be the Largest Railway Wagon in the World)