Perhaps the most important sub-variant was the Sea Hurricane.

The Hawker Sea Hurricane was a variant of the Hawker Hurricane. During World War II the Fleet Air Arm took on charge some 440 Sea Hurricanes, 60 of which were built new as Sea Hurricanes and the rest were conversions from former RAF Hurricanes some of which dated from 1938. The Sea Hurricane was initially deployed not for aircraft carrier operations but to protect merchant shipping. To combat German maritime-reconnaissance bombers, some ships were converted into CAMs (catapult aircraft merchantmen) which meant that a Hurricane fighter could be launched from the ship when danger approached. The biggest problem was that the fighter could not re-land on board, and so the pilot had to ditch it in the sea. The main areas of operation for the 'Hurricat' or 'Catafighters' were in the Mediterranean and Baltic. Later versions of the Sea Hurricane operated from aircraft carriers, being fitted usually with catapult spools and arrester hook, but by 1943 the Sea Hurricane had all but disappeared from service.

However, most Sea Hurricanes were not newly-built fighters but converted RAF types, and were deployed originally not for aircraft carrier operations but to protect merchant shipping. To combat German maritime-reconnaissance bombers, some ships were converted into CAMs (catapult aircraft merchantmen) which meant that a Hurricane fighter could be launched from the ship when danger approached. The biggest problem was that the fighter could not re-land on board, and so the pilot had to ditch it in the sea. The main areas of operation for the 'Catafighters' were in the Mediterranean and Baltic, but by 1943 the Sea Hurricane had all but disappeared from service.

Sea Hurricane MkIIc 835 squadron of HMS Nairana in 1942

Of the 14,533 production Hurricanes built, some had gone for service with other air forces, and Canadian Car and Foundry manufactured 1,451 Hurricanes between 1938 and 1943. In particular, Hurricane wartime production supplied 2,952 of these aircraft to the USSR, to aid its fight against the Germans on the Eastern Front. As a result of convoy shipping losses not all reached their destination. Other wartime deliveries  went to Egypt (20), Finland (12), India (300), Irish Air Corps (12), Persia (1) and Turkey (14), and total production in the UK and Canada amounted to 14,231. The first Hurricane sorties in Russia were made on 11 September,1941 in defense of Murmansk, pilots from France, Britain and America helping the Soviets in their task.

Versions
 Mk I          One Hurricane Mk I conversion; Catapult spools and arrester hooks
 Mk IA        50 Hurricane conversion; catapult spools only; specially produced for CAM fighter scheme - launched from CAM ships
 Mk IB        300 Mk I (merlin III) and 25 Mk IIA series 2 conversions; Catapult spools and arrester hook (MAC-ship service)
 Mk IC        Hurricane Mk I conversion with four-cannon wings; catapult spools and arrester hook
 Mk IIC       Arrester hook and naval radio equipment
 Mk XIIA    Canadian built navalised Mk XII, with Packard Merlin XXIX engine.

The Fleet Air Arm took charge of 537 Hurricanes and Sea Hurricanes between 1939-1945 primarily from the RAF, but at least one was delivered from the RCAF to RNDA 5MU in September 1942.

Once the Fleet Air Arm took delivery of the Hurricanes from the RAF, starting with 880 squadron in March 1941 and 804 squadron in April 1941 it then started the mamoth task of shipping the Hurricanes to operational squadrons in all theatres around the world. A large consignment was shipped out in HMS Furious to 807 squadron in Gibraltar on 1 July 1941 (eg V7301 and V7623). Whilst others were shipped to South Africa in SS City of Bombay on 9 January 1942 (eg Z4056). Half a year later further consignments were shipped out on SS Belgian Seaman to Takoradi from Liverpool on 30 June 1942 (eg BP709), and to Simonstown in SS Lt St Lonbert Brie thence to 800 sqn on HMS Indomitable in July 1942 (eg V7416). However, quite a number were lost with the HMS Eagle which sank on 11 August 1942.

Only sixty of all these aircraft were built as Sea Hurricanes, a batch of Mk.IIC's with 4-cannon wings built by Hawker and delivered between December 1942 and May 1943.  All other Sea Hurricanes were conversions from Hurricanes including veterans from Hawker's first production batch delivered to the RAF in 1938 and 1939. The oldest of the conversions was Hurricane L1663, originally delivered to 32 Squadron RAF in 1938 and later converted to a Sea Hurricane IB in March 1941.

Most operational squadrons last used the Hurricane between 1943-44, when they were relegated to second-line squadrons.

The last of the wartime delivered Hurricanes to serve in the Fleet Air Arm were in 774 squadron until February 1945 (eg LF630), in 771 squadron up until January 1945 (LF704) and the final one, LF630 returned to the RAF at BAFO Communication Flight in June, 1945.

Total Hurricanes and Sea Hurricanes delivered to the FAA 1939-1945:  537

Total: Hurricane I , Ia and Ib:    48
Total: Sea Hurricane Ib:           290
Total Sea Hurricane II:              42

The Fleet Air Arm Hurricane and Sea Hurricane saw significant operational activities in many theatres of the war. They were involved in Operation Harpoon, Operation Pedestal to Malta, Operation Ironclad to Madagascar, the Western Desert, and in convoy duties where the aircraft claimed a high number of enemy aircraft shot down. Hurricanes equipped 32 RAF squadrons, some with Fleet Air Arm pilots seconded to these RAF Fighter command squadrons, and shot down more enemy aircraft than all other aircraft combined during the Battle of Britain.

Often under-rated in favour of the Spitfire, the Hurricane was the main victor of the Battle of Britain. 620 Hurricane and Spitfire fighters, with another 84 fighter typs including from FAA 804 and 808 squadrons under the command of RAF Fighter Command, had to face the German air threat of 3,500 bombers and fighters. During the Battle, along with the Spitfire, it helped to force the Luftwaffe to use the Bf 109 to protect the poor performing twin engine Bf 110 escort fighter. As an indication of their value, the Hurricane accounted for 80% of all German kills during the Battle. The highest scoring Allied pilot of the Battle - a Czech named Sergeant Josef Frantisek, who claimed 17 victories - was a Hurricane pilot.

The Hurricat were mounted on and launched from a catapult at the ship's bows, the Hurricane was flown off on what was usually a one-way flight: after providing defence for the convoy there was no where for the pilot to land, which meant he was obliged to bailout, or ditch his aircraft as near as possible to the convoy, hoping to be picked up. Not all CAM ship aircraft were FAA Hurricanes, the RAF converted and operated a few of its own Hurricanes. The provision of long-range drop-tanks beneath the wings, introduced in August 1941 after the CAM-ships had been provided with more powerful catapults for the higher gross weight.

The first of the Sea Hurricanes to see service with the Fleet Air Arm arrived in February 1941 and were operating with front line unit 880 squadron from 15 March 1941. Overseas deliveries commenced with shipping in HMS Furious to 807 squadron at Gibraltar 1 July 1941 (eg V7301, V7623), Many shipped to Simonstown in SS Lt St Lonbert Brie thence to 800 squadron HMS Indomitable in July 1942 (eg V7416), some shipped to South Africa in SS City of Bombay 9 January 1942 (eg Z4056) and others shipped in SS Belgian Seaman to Takoradi from Liverpool 30 June 1942 (eg BP709). A significant loss occurred when Sea Hurricanes were sunk with HMS Eagle which was torpedoed on 11 August 1942 (eg V6854).

The Sea Hurricane Mk I were followed by about 300 Mk Is converted to Sea Hurricane Mk IB configuration, these having catapult spools plus a V-frame arrester hook: in addition 25 Mk IIA were modified as Sea Hurricane IB or Hooked Hurricane II fighters. Their initial role was a considerable improvement on CAM-ship deployment, for from October 1941 they began to go to sea aboard MAC-ships, these being large Merchant ships fitted with a small flight deck.

Sea Hurricane Mk IC fighters, introduced in February 1942 were conventional Mk I conversions with catapult spools and arrester hook; they had, however, the four-cannon wing of the land-based Hurricane Mk IIC. The Sea Hurricane Mk IIC, was intended for Fleet carrier operations and, consequently, was without catapult spools. This version was also used as hurri-cats. They introduced also to navy service the Merlin XX engine, and carried FAA radio equipment. Mk.IIC's with 4-cannon wings built by Hawker and delivered between December 1942 and May 1943. The Sea Hurricane Mk X - Canadian built Hurricane X converted to Sea Hurricane standards were all classified either Mk.IA or Mk.IB by the RN, even though all used the two-stage Packard Merlin 28.  Thet were all built with eight .303 machine guns. The Sea Hurricane Mk XII - Conversion of Canadian Hurricane XII for Royal Canadian Navy with full naval equipment. Packard Merlin 29 with twelve .303 machine guns. The last of the Sea Hurricane variants was the Sea Hurricane Mk XIIA, of which a small number were converted from Canadian-built Mk XIIs, and these were used operationally in the North Atlantic. Although the Sea Hurricane last saw service in 1945, Sea Hurricane NF670 was still extant on the East Kirby dump in 1956/57.