Buckingham Palace's swimming pool has been in the news this week following King Charles' decision to lower the temperature of the water, for environmental reasons.
According to The Sunday Times, the King's staff have revealed that the thermostat has been lowered and the temperature of the water has dropped.
Charles' change is no surprise and goes hand in hand with other eco changes he has made at official residences, such as Clarence House, where he has installed solar panels on the roof.
All of the talk of the palace's swimming pool uncovered other facts about the facility – including what royals can and can't wear for a dip in the blue waters.
Palace rules state that there is no strict clothing code for the pool, but due to the natural decorum of Palace residents, no overly revealing swimming attire is expected, meaning anyone taking to the water is likely to be wearing a swimsuit or modest swimming shorts as opposed to Speedos or bikinis.
The Buckingham Palace pool is a favourite feature of the residence for the royals, with many learning to swim in the water. Back in 2014, it was revealed that Princess Kate was taking her one-year-old son Prince George for weekly swimming lessons in the private pool.
The Princess of Wales was spotted back there again in 2015, just weeks before welcoming Princess Charlotte, and according to royal author Brian Hoey, Prince Philip used to swim regularly until he retired from official duties. It is also thought that William and Kate's youngest children, Charlotte and Louis, have also used the pool in the past.
Are the royal family good swimmers?
Behind closed doors, King Charles III's mother Queen Elizabeth II was an excellent swimmer, taking to the waters from just 10 years old.
According to Swimming World Magazine, the Queen started by swimming breaststroke and backstroke and quickly earned her first medal for swimming.
The young royal reportedly earned several lifesaving certificates over the years, and she received a badge recognising proficiency and grace in every stroke and in diving.
Ever the high achiever, Queen Elizabeth II was given an award for being the best female swimmer (for girls 14 years and younger).
Upon her rise to the throne, Her Majesty was a patron of the Amateur Swimming Association (known as British Swimming today), reportedly because she saw swimming not just as a competitive sport, but as an activity that benefits wellbeing.
Queen Elizabeth II passed on her talent to her son, King Charles III, who was often photographed frolicking in the sea during his younger years. Her granddaughter, Zara Tindall, is also a keen swimmer.
King Charles' son Prince William is also a talented swimmer, and captain of the water polo team during his time at the University of St Andrews, frequently travelling around the country to play other student teams.
He even shared in 2017 that the royals were a "family of swimmers," telling Eileen Fenton, who received an MBE for voluntary services to swimming all the details of their prowess.
Eileen told the Press Association: "He said that he and his wife make sure the children can swim and they all go and they swim quite well."
We're pleased to hear that the pool at Buckingham Palace is likely used often, though Princess Kate recently revealed she prefers outdoor cold water swimming, and the ocean is Queen Camilla's favouite spot for a swim.