The Diamond Jubilee River Pageant features more than 1,000 historic vessels, steam boats, barges and tugs.
With everything from dragonboats to one-man kayaks, the Thames waterway will be a medley of all things maritime.
Here are some of those to look out for:
The pageant's lead vessel is a floating belfry with a new set of eight church bells cast at the Whitechapel Bell foundry especially for the Diamond Jubilee celebrations.
The bells are named after senior members of the Royal Family - Elizabeth, Philip, Charles, Anne, Andrew, Edward, William and Henry - and will be answered and echoed by ringing from the riverbank churches along the route. After the pageant, the Royal Jubilee Bells will be housed at the church of St James Garlickhythe.
The £1m Gloriana will lead the manpower squadron of the pageant, ahead of the Queen's barge. It will be powered by 18 oarsmen including Olympians Sir Steve Redgrave and Sir Matthew Pinsent.
Corporal Neil Heritage, who lost his legs while serving in Iraq, and three other military service personnel who suffered life changing injuries, will be among the elite team.
Four of the rowers on the 94ft gold leaf barge are members of the Paralympic rowing squad including Pamela Relph. The vessel features wood from sweet chestnut trees grown on the Prince of Wales's private estate.
Spirit of Chartwell
Carrying the Queen and other key royals including the Duke and Duchess of Cambridge, the Spirit of Chartwell, the Royal Barge is lavishly decorated with replica carvings. With a majestic red, gold and purple colour scheme, the vessel's design will echo the richly decorated royal barges of the 17th and 18th centuries.
It displays a gilded prow sculpture of Old Father Thames, a pair of scaly, sharp-toothed classical dolphins - a symbol of the Thames - and the royal cipher at the centre. A red, velvet banner decorated with a version of the royal coat-of-arms made from more than half a million gold-coloured buttons hangs from the stern.
The Queen and Duke will be seated on the vessel's top deck in ornate chairs under a gold-coloured canopy.
Inside it has been designed to evoke the grandeur of the 1929 Cote d'Azur Pullman railway carriage.
The Royal barge has been be decked out with nearly 10,000 flowers including 4,000 red carnations, 2,100 Darcey roses, 1,000 Patience roses and 500 purple and red sweet peas.
This paddle steamer will be ferrying the Duchess of Cambridge's family - her parents Michael and Carole and siblings Pippa and James.
The Elizabethan is described as having "the unique exterior of a 19th century paddle steamer coupled with the interior of a top London restaurant and night club".
The Duke of York, Princess Beatrice, Princess Eugenie, the Earl and Countess of Wessex, the Duke and Duchess of Gloucester and Prince and Princess Michael of Kent will sail on the Havengore joined by Mayor of London Boris Johnson and former prime minister Sir John Major and his wife Dame Norma Major.
The Havengore was used to transport Sir Winston Churchill's body along the Thames on the day of his state funeral in 1965.
St Michael's Mount Barge
Built in 1740, the St Michael's Mount is one of the oldest boats on the river and the oldest boat still in commission in Britain.
The barge once carried Queen Victoria - the only other British monarch to reach a diamond jubilee - ashore from the Royal Yacht to St Michael's Mount in Cornwall in 1846.
It was also used as a command practice craft for beach landings during the Second World War. Among those on board will be a crew of Island residents and workers including castle steward Adam Poole, mount gardener Claire Hillage and head boatman Dave Ladner.
Dunkirk "little ships"
Some 40 Dunkirk "little ships" - still waterborne 72 years on - are taking to the Thames, reuniting vessels that evacuated Allied troops from French beaches in 1940.
On board the Nyula will be 95-year-old Vic Viner, thought to be the sole survivor of the Navy's rescue operation at Dunkirk.
This half size replica of a Viking Longboat travelled down to the Thames from the Shetland Islands. All rowed boats will "toss oars" in salute to The Queen as they pass her.
In the Avenue of Sail where vessels too large to travel with the rest of the flotilla are moored is the 127-year-old Amazon. The Amazon took part in the Royal Fleet Review at Spithead for Queen Victoria's Diamond Jubilee in 1897 - the only Pageant vessel thought to have done so.