Relatives of those killed in the Royal Navy’s worst wartime accident will be among those marking its centenary.
HMS Vanguard exploded and sank in Scapa Flow off Orkney on July 9 1917, with the loss of 843 lives.
Commemorative events will be attended by 40 descendants of the men who died.
A number of vessels will take part in a wreath-laying service over the wreck site of HMS Vanguard on Sunday morning.
This will be followed by a service at the Lyness Royal Naval Cemetery on the island of Hoy, where 41 of the ship’s crew are buried.
The day will culminate with a special night watch service at St Magnus Cathedral in Kirkwall.
Starting at 11pm, it will mark the moment when the ship was destroyed by the explosions on board.
During the service, the White Ensign that was recovered by the Royal Navy’s Northern Diving Group (NDG) will be presented to the people of Orkney.
The NDG worked alongside a team of volunteer civilian divers to carry out a sight survey and replace the flag, laid by the Royal Navy in 2009, with a new White Ensign.
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Naval Regional Commander Scotland and Northern Ireland, Captain Chris Smith said: “The history of the Royal Navy and Scapa Flow are tightly entwined.
“Last year, we recognised the huge sacrifice made by our sailors at the Battle of Jutland and commemorated the loss of HMS Hampshire.
“Next month we will recognise the achievement of Squadron Commander Edwin Dunning with his first-ever landing of an aircraft on a ship at sea and his subsequent death a few days later, but this weekend we are firmly committed to commemorating the tragedy that was the loss of HMS Vanguard.
“The devastating explosion, completely accidental rather than a result of enemy action, was a shock when it happened and the tragic loss of more than 840 lives is still felt through their descendants and those in Orkney who feel passionately that we should mark the centenary in appropriate fashion.”
During the winter of 2016/17 a team of volunteer divers were granted a licence to conduct an underwater photography, videography and 3D photogrammetry model of the wreck site.
Organiser Emily Turton, of Huskyan Dive Charters, said: “The data gathered by the team has allowed a greater understanding of the layout of the site, and also allows the wider community a chance to see HMS Vanguard after 100 years underwater.”