The Port of Liverpool is the enclosed 7.5 miles (12.1 km) dock system that runs from Brunswick Dock in Liverpool to Seaforth Dock, Seaforth, on the east side of the River Mersey and the Birkenhead Docks between Birkenhead and Wallasey on the west side of the river. The port was extended in 2016 by the building of an in-river container terminal at Seaforth Dock, name Liverpool2. The terminal can berth two 14,000 container Post-Panamax ships.
Garston Docks, which are in the city of Liverpool, are not a part of the Port of Liverpool. The working docks are operated by Mersey Docks and Harbour Company, the docks to the south of the Pier Head are operated by the Canal & River Trust, the successor to former operator British Waterways.
Liverpool's first dock was the world's first enclosed commercial dock, the Old Dock, built in 1715. The Lyver Pool, a tidal inlet in the narrows of the estuary, which is now largely under the Liverpool One shopping centre, was converted into the enclosed dock. Further docks were added and eventually all were interconnected by lock gates, extending 7.5 miles (12.1 km) along the Liverpool bank of the River Mersey. From 1830 onwards, most of the building stone was granite from Kirkmabreck near Creetown, Scotland.
The interconnected dock system was the most advanced port system in the world. The docks enabled ship movements within the dock system 24 hours a day, isolated from the high River Mersey tides. Parts of the system are now a World Heritage Site.
From 1885 the dock system was the hub of a hydraulic power network that stretched beyond the docks.