The Royal Yacht Britannia, also known as Her Majesty’s Yacht Britannia, is the longest-serving carrier of the British royal family.
The Yacht is the former Royal sea carrier of the British monarch, Queen Elizabeth II. It served her majesty for a total of 43 years (1954-1997) and is said to have traveled more than a million nautical miles across the globe, transporting members of the Royal family by Sea.
Now retired from royal service, Britannia is permanently berthed at Ocean Terminal, Leith in Edinburgh, Scotland.
While in active service, the Britannia had a capacity of 250 guests. A platoon (20-50 soldiers) of Royal Marines would also be present whenever members of the Royal family were on board for security reasons.
The Royal Yacht is now a top attraction in Scotland, bringing around 300,000 visitors annually.
Source: Royalyachtbritannia and Wikipedia