Palace officials Wednesday announced details of a massive pageant on London's River Thames to mark the Queen's Diamond Jubilee year.

Plans call for roughly 1,000 boats of various sizes to gather June 3 for an unprecedented tribute to the Queen, who is marking the 60th year of her reign.

The flotilla will be over 11 kilometres long and include barges on which original works composed for the jubilee will be performed. The event is planned to celebrate Britain's fabled maritime history.

The Queen, her husband, Prince Philip, and other senior royals, likely including Prince William and his wife, Kate Middleton, will travel aboard a royal barge, The Spirit of Chartwell, an opulent cruising vessel that regularly plies the River Thames.

The barge will be decorated with flowers from the Queen's gardens, with an emphasis on the royal colours, red, gold and purple.

Pageant master Adrian Evans said the royal barge "must be a jewel — the most magnificent vessel in the flotilla."

Organizers say the flotilla, one of the largest ever assembled on the river, will include rowboats, working vessels and pleasure craft. All boats will be decorated, including kayaks and canoes.

The procession will cover about 22 kilometres, from Hammersmith in west London to the Greenwich Royal Naval College in the east, and will include a vessel, the Amazon, used in Queen Victoria's Diamond Jubilee in 1897.

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Officials expect roughly 20,000 people to be aboard various craft, with many more lining the river banks and an international audience watching the spectacle on TV and online.

Prince Charles will be patron of the event, which is being paid for by the Thames Diamond Jubilee Foundation, a privately funded charitable trust raising money for a variety of jubilee-related events.

The river pageant will be a focal point of a four-day holiday weekend with festivities throughout Britain.

A number of other celebrations are planned throughout the jubilee year, with the Queen and Philip planning to travel throughout Britain.

The Queen's children and grandchildren plan to travel around Commonwealth countries, including Canada, to mark the event.