Part of Swansea Docks (nprn 580), Queen's Dock is the most recent, opening in 1920 for the import of crude oil for the nearby refinery of the Anglo-Persian Oil Company (later British Petroleum or BP) at Llandarcy (nprn 91695). From the mid-1930s, around 6 million gallons of sea water per hour were drawn from the nearby King's Dock (nprn 419502) for cooling at the nearby Tir John Power Station (nprn 415587) and returned to the larger Queen's Dock. The water was carried in two large concrete-lined tunnels, each about 3m in across and about 1km long, cut through solid rock at depths of up to 90m.
(Sources include "A Guide to the Industrial Archaeology of the Swansea Region", Association for Industrial Archaeology, 2nd Edition, 1989)
B.A.Malaws, RCAHMW, 25 October 2013.