HMS Thetis was an Apollo-class second-class protected cruiser of the Royal Navy, launched on 13 December 1890.

[2] She was commissioned at Chatham on 25 November 1902 with a complement of 273 officers and men for service on the China Station.

[3] She left Sheerness on 14 December, stopping in Gibraltar, Malta, Port Said, Aden and more places before arriving in China the following year.

Laden with concrete, she was deliberately sunk at 51°21′28.66″N 3°11′50.64″E / 51.3579611°N 3.1974000°E / 51.3579611; 3.1974000 as a blockship in attempt to block the canal in the Zeebrugge Raid during the First World War, on 23 April 1918.

Post-war, Thetis was beached on a sandbank west of the harbour entrance.