Director Danny Boyle has announced a nationwide beachside event to mark the centenary of the end of World War One.
Members of the public are invited to assemble at dozens of beaches around the UK on Armistice Day, 11 November.
A large-scale portrait of a casualty from the war will be drawn into the sand at low tide at each location and washed away as the tide comes in.
Boyle has also commissioned a new poem by poet laureate Carol Ann Duffy, to be read by people on the beaches.
The event, titled Pages of the Sea, is part of 14-18 NOW, the UK's official arts programme to mark the World War One centenary, which has been running since 2014.
The Oscar-winning film-maker and mastermind behind the London 2012 Olympic Games opening ceremony has created the event as an "informal nationwide gesture of remembrance".
The public will be asked to join in by creating silhouettes of people in the sand, remembering the millions of lives lost or changed forever by the conflict.
Many of those who served in World War One left by sea, and Boyle said he felt beaches were the perfect places for a memorial.
"Beaches are truly public spaces, where nobody rules other than the tide," he said. "They seem the perfect place to gather and say a final goodbye and thank you to those whose lives were taken or forever changed by the First World War.
"I'm inviting people to watch as the faces of the fallen are etched in the sand, and for communities to come together to remember the sacrifices that were made."
An initial 12 locations have been announced, from Waulkmill Bay on Orkney to Porthmeor Beach in St Ives, Cornwall. More will be confirmed.
There will also be an online gallery of portraits of some of those who served in World War One - for people to select someone to say a personal goodbye to on the beach or via social media if they can't get there.
The images are from the Imperial War Museum's Lives of the First World War project, which aims to tell the stories of eight million people from Britain and the Commonwealth who served.
Boyle has recently pulled out of directing the new James Bond film and was asked at the launch if he had any words of advice for Cary Fukunaga who has taken on the job.
More time without Bond
"We're talking about real heroes today rather than fictional ones," he said.
But he admitted stepping away from Bond gave him more time to focus on the anniversary plans.
"I do have a bit more time to dedicate to this, which is great. I'm very pleased about that because it's something which is very dear to my heart."
"My involvement in it would have been slightly compromised by that (Bond) workload.
He said it was a "proper privilege" to create Pages of the Sea, where you could hope to "connect with everybody in the country in some way, as much as you can, rather than through your normal channels, like the box office".