The Oslofjordtunnel is one of the longest underwater tunnels of its kind in Northern Europe; it is 7.2 km long and reaches a depth of 134 metres below sea level, with a maximum gradient of 7%.
The Oslofjordtunnel is one of the longest underwater tunnels of its kind in Northern Europe. It is 7.2 km long. This is with a maximum gradient of 7%. It reaches a depth of 134 metres below sea level. This is with a maximum gradient of 7%.