9 September marks 63 years and 216 days since the Queen came to the throne, making her the longest reigning monarch in British history, and London's celebrating with a historic flotilla.
Rowing barges Gloriana and Havengore, which were part of the Queen’s Diamond Jubilee River Pageant in 2012 and fireboat Massey Shaw take to the river as part of a celebratory procession. The Massey Shaw will shoot jets of water into the air, adding to the spectacle.
The historic vessels will be joined by passenger boats and leisure cruisers.
If you're in the area at midday, you may well hear the procession kicking off — it'll begin with vessels sounding their horns for one minute, followed by Tower Bridge opening as a mark of respect and a four gun salute as it passes HMS Belfast.
That's your cue to get down to the river, flags a-waving and hands applauding, as Londoners are being asked to make as much noise as possible as the flotilla passes.
The Royal River Salute is part of Totally Thames Festival, which takes place throughout September.
The Royal River Salute takes place on 9 September. The procession begins east of Tower Bridge at midday, making its way down the river and ending at Houses of Parliament approximately 30 minutes later, where there will be a final fanfare and three cheers.