The dark waters of the Thames estuary are the last resting place of a secret sunken navy - from 17th-century galleons to Second World War victims of the Luftwaffe.
Now the London Port Authority is deepening shipping channels to allow some of the world's biggest boats to approach the capital. As a result of the dredging, historic shipwrecks are again seeing the light of day.
The HMS London should have been an auspicious ship; she was one of the first vessels of Charles II's reformed Royal Navy, having been part of the fleet that brought him back from exile in the Netherlands in 1660 to end the anarchy that had reigned since Cromwell's death two years previously. Yet she was anything but lucky.
When she was lost in 1665 all was peaceful: we were between squabbles with the Dutch. The London was sailing up the river with 300 men and noblemen on board - and 14 tons of gunpowder.
Either traders had sold the ship cheap, unstable powder, or a flame - from a candle carried by a crew member - blew up the warship.