Salvaging HMS Bulwark after 21 years war time mystery explosion which cost 760 lives . Five miles from Sheerness salvage operatons from the former monitor Humber have commenced on the wrecked HMS Bulwark , the warship sunk by a mystery explosion with the loss of 780 lives in the early days of the Great War . Divers have commenced their examinations of the wreck , which lies seven fathoms down on the bottom of the River Medway , and a 60 ton steam crane has been erected to remove the valuable armoured steel plates and gun turrets which are to be blasted away . Photo shows , tthe salvage ship ' Humber ' and her 90 ton crane moored over the HMS Bulwark . 1 August 1935