Channel Tunnel is the longest underwater tunnel

The Channel Tunnel is 31.35 miles long under the English Channel.

The tunnel runs beneath the English Channel between UK and France.

The railway tunnel measures 50.46 kilometres from end to end.

37.9 kilometres of the tunnel run underwater beneath the sea.

The tunnel reaches 75 metres below sea level at its deepest point.

Faults and variations in chalk posed challenges for tunnel builders.

The first tunnel proposal was in 1802, with horse-drawn coaches.

Military fears delayed tunnel projects due to invasion concerns.

Eurotunnel initiated the modern Channel Tunnel project in 1988.

The Channel Tunnel opened in 1994, linking Britain and France by rail.

Eurotunnel operates passenger, freight, and vehicle shuttle trains inside.

Trains travel at maximum speeds of 160 kilometres per hour for safety.

A lorry fire in 2015 closed the tunnel and halted all services.

The Channel Tunnel still connects Great Britain and mainland Europe today.