A volunteer team has been given special permission to dive on the wreck of the Royal Oak in Orkney's Scapa Flow.
The ship - which was sunk by a U-boat in Scapa Flow in October 1939 with the loss of more than 830 men and boys - is protected as a war grave.
But the divers have been allowed to gather images and information for use in 80th anniversary commemorations.
It follows similar projects by the same group on the wrecks of the Royal Navy ships HMS Hampshire and HMS Vanguard.
Stromness-based dive boat owner Emily Turton told BBC Radio Orkney "diving was banned on Royal Oak in 2002" to protect it.
"Very little access is given to British war graves, and it has to be by special licence," she said.
She said she had been working closely with the Royal Navy northern diving group and the Royal Oak Association.
"We asked what they would like to see," she said.
Ambitious plans to produce video and 3D images were delayed following the theft of a laptop and two external hard drives from the team.
The equipment was taken during a break-in at a flat in Stromness, which prompted a £1,500 reward for its return.
Emily Turton said the theft had been "devastating", but she said she hoped it would be possible to recover the raw data, and recreate the processed images.
Gareth Derbyshire, chairman of the Royal Oak Association, said the project was "an important means of ensuring that the history of the ship and the circumstances of its loss were available to future generations.
The last of the survivors of HMS Royal Oak died in December 2016.
Diving work on the wreck is now almost complete.
The next phase of the project will see all the data that has been gathered being collated and processed.
A comprehensive survey report is due to be produced before the end of the year.
The dive team will also present their findings to the public.