Some of the most iconic photos of royals have been taken aboard the Royal Yacht Britannia, from then-Prince Charles and Princess Diana's honeymoon in 1981 to Zara Tindall's pre-wedding party in 2011.
While it is largely associated with fond memories, the yacht also had a more sinister purpose. According to the website, it was intended as an escape route off the coast of Scotland, should we ever be unfortunate enough to descend into a nuclear war.
Escape plan
Speaking of the ship's multiple purposes, it stated: "Although designed and built with hospital ship capability, this was never used in the vessel’s lifetime.
"The closest the Royal Yacht ever came to operating in such circumstances was during the 1986 civil war in Aden when she was used to evacuate over 1000 refugees. Recognised as a non-combatant Royal Navy ship, Britannia was able to enter sensitive territorial waters without risk of worsening the conflict.
"It was intended that, in the event of a nuclear war, the Queen and Prince Philip would use the Royal Yacht as a refuge in the waters off the North West Coast of Scotland."
While the late Queen and her husband only embarked on the luxury yacht for the first time in May 1954, they made several other visits before their deaths in 2022 and 2021, respectively.
In fact, it served as a true home from home for the royals, who reportedly even enjoyed separate bedrooms and sitting rooms. The late monarch once described the Royal Yacht as the "one place I can truly relax."
Decommissioned yacht
Meanwhile, Elizabeth's son King Charles was among the first to sail on the yacht on its maiden voyage from Portsmouth to Malta in April 1954. It is possible that Charles and his now-wife Queen Camilla would have inherited his parents' nuclear war escape route.
However, the plans would need to be tweaked to involve a different yacht, given that The Royal Yacht Britannia was decommissioned in 1997.
After travelling over a million nautical miles in 44 years, the Royal Yacht Britannia went on a farewell tour around the UK before being permanently berthed in Leith, Edinburgh, where it now serves as a popular visitor attraction.
To mark the decommissioning of the iconic yacht that featured in several royal historic moments, the clocks on Britannia were stopped at 15:01, which was when Queen Elizabeth II was piped ashore for the last time.
In a sign of the emotive farewell, Her Late Majesty publicly shed a tear as The Band of HM Royal Marines played 'Highland Cathedral.'