By Dan Rivers
London (CNN) - The UK Navy's largest warship will act as a helicopter landing platform and logistics hub.
The 21,500-ton helicopter carrier will also be home for 400 military personnel providing security in Greenwich Park, where the equestrian events and modern pentathlon will take place.
It is at the heart of a military run Olympic security operation
CNN's Senior International Correspondent Dan Rivers goes aboard the HMS Ocean. Click the video player above to hear the story.