Royal Navy and Royal Marines amphibious experts and veterans are trying to finally find the 'lost wreck' of the Falklands war.
Using research, computer modelling and a detailed understanding of weather and sea conditions, they are hoping to find where Landing Craft Foxtrot 4 was last sighted.
Six crewmen were killed when the vessel was bombed on 8 June 1982, although the tragedy is often overshadowed by the attack on the RFA ships Sir Galahad and Sir Tristam earlier that day.
The attacks on the ships were the single biggest loss of British lives in the Falklands war.
However, the fate of Foxtrot 4 still resonates, with HMS Albion commemorating the 40th anniversary of the tragedy.
Sailors and Royal Marines from the ship gathered on the flight deck for a thanksgiving service as the ship returned to Plymouth following the Queen's Platinum Jubilee celebrations.
They were joined by Rear Admiral Jeremy Larken, commanding officer of HMS Fearless, Albion's predecessor and Foxtrot 4's 'mother ship' in 1982.
Admiral Larken said it was a "rich privilege" to join HMS Albion for the service.
"The remembrance of Colour Sergeant Brian Johnston and his team should be forever with us as a vivid example of the risks we are invited [to] take in war and take gladly – and of the ultimate sacrifice that for some is taken," he said.
Colour Sergeant Johnston earned a posthumous Queen's Gallantry Medal for his action in rescuing sailors from HMS Antelope earlier in the Falklands conflict.
This resulted in rescuing more than 100 sailors despite fires raging on the ship, as well as the threat of an unexploded bomb.
To this day, a landing craft, Foxtrot H, is named in his honour.
Sergeant Gavin Smith, Royal Marines, said it is "an honour" to remember the crew of Foxtrot 4.
Watch: Memorial service held for two ships attacked during Falklands conflict.
There has never been a determined effort to find Foxtrot 4, although Royal Navy survey vessels visiting the Falklands have conducted occasional searches.
That may change now thanks to a small team of Falkland veterans, including Admiral Larken, as well as serving personnel dedicated to pinpointing the wreck site.
After the craft, which was ferrying Land Rovers and Royal Signallers from Goose Green to Fitzroy, was bombed, the surviving two crew and nine soldiers were rescued by helicopter.
It was attempted to take the landing craft undertow and the crew struggled until almost first light on 9 June – when the boat was finally abandoned.
"The locations of all other ships lost in the conflict are known," said former HMS Fearless and 4th Assault Squadron landing craft officer Lieutenant Colonel Richard Thurstan.
"The men lost on them have graves at sea that their families and friends can identify.
"The men of Foxtrot 4 have no known grave other than the sea – and finding her would bring overdue closure for the families."