Queen Elizabeth will ride on Royal Yacht Britannia's tender during her Diamond Jubilee Pageant.
The British monarch is set to board the tender - a small support boat to a larger craft - at Chelsea Pier at the start of the river procession on June 3.
The vessel is all that remains of the queen's beloved yacht, which was decommissioned in 1997, and she famously shed a tear at the ceremony in Portsmouth.
The tender will reportedly carry the monarch, the Duke of Edinburgh, the Prince of Wales and the Duchess of Cornwall.
The boat will transport the royal party 800 yards downstream to Cadogan Pier, where they will then board the new Royal Barge, the Spirit of Chartwell - a present to the queen given to her in celebration of her Diamond Jubilee - where they will be met by the Duke and Duchess of Cambridge and Prince Harry.
The royal barge will lead the procession, which is expected to include 1,000 vessels in the pageant and draw crowds of over a million watching from the riverbank.
Meanwhile, thousands of police officers have been drafted in for the pageant to endure it runs smoothly and with no disruptions.
At least 5,500 officers and 7,000 stewards will line the river as London comes to a standstill on June 3 for the historic flotilla.