HMS London on bottom of Thames
From This Is London
The largest-ever post-war salvage operation on the Thames has discovered seven shipwrecks up to 350 years old.
They include a warship that was blown up in 1665, a yacht converted to a Second World War gunboat, and a mystery wreck in which divers found a personalised gin bottle.
The vessels, in the Thames Estuary, are just some of about 1,100 ships which went down in the whole of the river.
The salvage by Wessex Archaeology and the Port of London Authority, which regulates the river, was both historical and practical.
Jagged metal from the wrecks which stick out of the mud, silt, and gravel act as a 'can-opener' that can split apart vessels, especially large container ships which can skim within half a metre of the riverbed.
The operation was filmed for the BBC and took four months, using a dozen divers who used 3D survey equipment to locate the wrecks in near-zero visibility.