VOYAGE INTO TERROR
The former pleasure ship was crammed with some 10,000 German refugees and wounded. It was only designed to carry 1800 passengers and crew.
But such was the desperation of those seeking refuge ahead of the unstoppable advance of the Red Army that it was standing room only aboard the ship as it slipped out of the Polish port of Gotenhafen (Gdynia) on a cold winter's day.
The MV Wilhelm Gustoff had been requisitioned by the German army at the start of the war as a transport and barracks ship. Now it was being used in Operation Hannibal - the evacuation of the German enclave of Danzig. It departed the port on January 30, 1945 in the company of another liner, the Hansa, and two torpedo boats as escorts.
Just hours later the Gustoff - which had mysteriously turned on its navigation lights to avoid collision - was sunk by three torpedoes fired by the Soviet submarine S-13.
Only one lifeboat was able to be cut loose before the liner went down 40 minutes later.
Some 9400 people - including 5000 children - died either in the wreck or fridgid waters.
Only 1250 were pulled from the water alive.
This is history's largest loss of life from a ship sinking.
The wreck was classified as a war grave after several attempts to loot its remains.
GOLD FEVER
The location of the MV Wilhelm Gustoff has never been a mystery. It is one of the largest wrecks in the Baltic.
Part of the mythology surrounding the ship can be traced back to how a number of technicians working on secret weapons programs, such as the V2 missile program, were among its evacuees. They had been stationed at remote Baltic facilities, far from the prying eyes of allied reconnaissance aircraft.
But Polish authorities have long since established a 500m radius 'no-dive' zone around the shattered remains of the ship to protect it from looters and treasure hunters seeking, among other things, Russia's legendary dismantled 'amber room'.
Sayers, 61, says he was granted permission to dive on the wreck in 1988 to place a memorial there and recover a handful of objects for a survivors' museum in Kiel, Germany.
He says he found a porthole with metal bracing attached, suggesting it came from a 'strong room' where the treasure could have been stored.
TALES FROM BEYOND THE GRAVE
Sayers claims he has since spoken to the ship's radio officer. Rudi Lange, one of the few crew to survive, reportedly told Sayers he saw crates being secretly stashed by armed guards aboard the ship while it was at its Polish dock.
It's a story he's since turned into a novel, Baltic Gold.
"We know from first hand accounts a whole load of lorries turned up alongside and transferred a cargo of high security on board on the ship," Sayers told the Daily Star.
"Rudi Lange went down onto the quay side to have a smoke and just happened to be there when the gold bullion transport arrived. He did not know what was being taken on at first ... It was not until 1972 when he met up with another survivor who was one of the guards who had been tasked with looking after the gold and he revealed what was in those huge cases."
Sayers says he believes it is three tonnes of Nazi stolen gold bars.
"The Nazi gold bullion was smuggled out of Königsberg. It is a fascinating story which has followed me for the whole of my life," he says.