The discovery of the tunnel has helped archaeologists and historians to piece together a more accurate picture of what went on in the Ponar forest in Lithuania during the war.
The tunnel was used as an underground escape route by Jewish prisoners-of-war held captive by the Nazis. It was constructed by 80 Jewish prisoners-of-war who had been forced by Nazi officers to dig up and burn bodies of those who had died at Stutthof concentration camp, a couple of which were relatives of the diggers.
"They were able to salvage tools from the bodies which they used to dig the tunnel," McClymont said.
The prisoners used pliers, a spoon and cups to dig the tunnel from the underground bunker which served as their living quarters, under a barbed wire fence and through more than 30m of sand.
Only 12 of the 80 made it out of the camp through the tunnel. Of those who escaped 11 joined the resistance groups against the Nazis.
McClymont says the project is important because it allowed the victims of to be honoured appropriately according to the Jewish faith.
"There are all these people who didn't get properly memorialised. They were just a number, one of six million."
Many of McClymont's colleagues were of Jewish heritage and at least two had relatives who had died in Lithuania during the war.
The entrance to the tunnel was discovered in 2004, and the recent project used geophysics techniques similar to medical imaging to reveal the whole tunnel without disturbing the remains that lie underground.
The story of the tunnel is a chilling reminder of the horrors of World War II.
"It's hard to imagine how people did that to each other only 70 years ago," McClymont said.
