On 9th of July 1917 HMS Vanguard exploded in Scapa Flow (the result of an internal explosion of faulty cordite), killing 804 men.
HMS Vanguard #OnThisDay
Not Just Flotsam and Jetsam
By far the largest number of marine related artefacts displayed are from the German fleet which was scuttled in Scapa Flow on 21st of June 1919.
