HMS Ocean (L12) is the 6^th ship to carry the name in the RN and is designated a Landing Platform, Helicopter, the only one of her class. She is designed to support amphibious landing operation.

Constructed in the mid 1990s at Govan shipyard on the Clyde but fitted out at Barrow in Furness prior to trials and subsequent acceptance into service, Ocean commissioned in September 1998 at her Devonport.

Designed to provide the amphibious assault capabilities last offered by HMS Albion  and HMS Bulwark, Ocean can deploy a Royal Marine Commando group from 3 Commando brigade, supported by aviation and landing craft assets. The ships company includes 9 Assault Squadron from 1 Assault Group Royal Marines. The ship is also capable of limited Anti-Submarine Warfare activities, supporting afloat training and acting as a base facility for other embarked forces including counter terrorism units.

The air group, of up to 12 Sea King HC-4 medium-lift helicopters, six Lynx AH-7 light-lift/anti-Tank helicopters, and four Mk5 landing craft, is provided by the Commando helicopter Force but she can also support the Westland WAH-64 Apache operated by the Army Air Corps and RAF helicopters, including the Chinook.

Ocean can transport up to fifteen fixed wing Harriers of Joint Force Harrier in the ferry role but is unable to operate as a fixed wing aircraft carrier.