HMS Vindex was a Royal Navy seaplane carrier during the First World War, converted from the fast passenger ship SS Viking.

The ship spent the bulk of her career operating the North Sea, where she twice unsuccessfully attacked the German Zeppelin base at Tondern and conducted anti-Zeppelin patrols.

[4] The ship carried 475 long tons (483 t) of coal which meant that she could steam for 995 nautical miles (1,843 km; 1,145 mi) at a speed of 10 knots (19 km/h; 12 mph).

[9] Vindex was fitted with a 64-foot-long (19.5 m) flying-off deck forward, intended for aircraft with wheeled undercarriages, and a prominent hangar aft.

[5] The ship was built in 1905 by Armstrong Whitworth, Newcastle upon Tyne as the Viking, a fast passenger ferry for the Isle of Man Steam Packet.

The two ships carried eleven Babies between them, each armed with 65-pound (29.5 kg) bombs, but eight failed to take-off; one hit the mast of an escorting destroyer and one had to return due to engine trouble.

[6] On 2 August one of her Bristol Scouts unsuccessfully attacked the Zeppelin LZ 53 (L 17) with explosive Ranken darts, the first interception of an airship by a carrier-based aircraft in history.

[5] [3] Vindex was to provide aerial reconnaissance with two of her seaplanes for a Coastal Motor Boat raid on 22 October 1916, but the operation was aborted because of fog.