The Warnow Tunnel (also known as the Warnow River Crossing and the Warnowquerung in German) is a road tunnel 790 m long which connects the east and west bank of the Warnow river in the Hanseatic city of Rostock in Mecklenburg-Vorpommern, Germany.
It is Germany's first toll road in modern times and was opened on 12 September 2003 by Federal Transport Minister Dr. Manfred Stolpe.
The tunnel was built using a technique known as immersed tube Construction: the main part of the tunnel consists of six prefabricated concrete conduits which were formed and poured in a temporary drydock nearby, floated out into the river and lowered into a dredged channel in the river bottom. This is a technique apparently pioneered in the Detroit River in construction of the Detroit–Windsor Tunnel in 1930, and replicated for sub-aqueous tunnels ever since.
The 50-year operating concession is held by Warnowquerung GmbH & Co. KG, which is 70% by the Australian investment company Macquarie Infrastructure Group which operates many tolled roads worldwide.