One of the most daring clandestine operations of World War II was the 1944 sinking of the Norwegian ferry Hydro, with its purported cargo of heavy water destined for the Nazis’ secret atomic bomb project. Heavy water is a form of water with a unique atomic structure and properties coveted for the production of nuclear power and weapons. Although the mission was declared a success, no one has established whether heavy water was actually on board. In cooperation with NOVA, ProMare plunged 1,300 feet beneath a remote Norwegian lake to find the answer to “Hitler’s Sunken Secret. ”
Exploring the bottom of Lake Tinn with a remotely operated vehicle, ProMare, NOVA and Sperre AS located the well- preserved ship along with evidence of a mysterious cargo in steel drums. Analysis of the contents of one of those drums solved the longstanding mystery about the role that the Allies played in preventing a Nazi nuclear bomb. The cargo was indeed heavy water. However, the Allies had no way of knowing that the Nazi nuclear program was a civilian program with little funding, and that the military regime had not considered nuclear weapons practical to construct in a time-frame that would allow them to win the war.
Norsk Hydro began producing heavy water at Vemork in 1934. During the German occupation of Norway, the Norwegian resistance made several attempts to stop the Germans producing increased amounts of heavy water. There was an attack in the autumn of 1942 using a glider, which failed. In February 1943, a group of members from the local resistance succeeded, and after meticulous planning, they climbed down the steep valley sides and sabotaged the heavy water facility. The story is told in the Norwegian film “Kampen om tungtvannet” and the American film production “Heroes of Telemark.”
The Germans rebuilt the plant, and in November American bombers flew over Vemork and bombed the valley, but the plant was only partially damaged. This last attack caused the Germans to move heavy water production to Germany. The resistance successfully sabotaged German plans by placing a time-bomb on board the ferry, Hydro, that was to transport the heavy water over Lake Tinn. On February 20, 1944, as she was crossing the deepest part of the lake, the ferry Hydro exploded, destroying the last of the German’s heavy water.
The Lake Tinn Project in the news
The National WWII Museum published an article here.
America’s official Norway site published an article here.