The Norwegian navy spent five years searching for the U-864 and in October 2003 it finally found the German World War II blockade-breaking submarine. Two years later divers recovered a cast-iron bottle: it contained mercury, one of 1,857 that were still in the vessel. After almost two years examining the site, it was clear that the highly toxic canisters were leaking and contaminating the water and seabed -- only four kilometers away from Fedje, an island near the port of Bergen.
Around four kilograms of the toxic material has escaped into the sea this year alone and the rate is increasing. It is now forbidden to fish in the vicinity of the wreck, which contains around 65 tons of mercury. Fish with a higher concentration of mercury have already been caught in the area. The danger is that the poison could eventually pass up the food chain, and be ingested by humans.
"It is the amount that makes this case truly remarkable," says Ane Eide Kjeras, a spokeswoman for the Norwegian Coastal Administration (Kystverket). The body is now recommending that the U-864 be buried under sand and concrete. The U-boat from the dying months of the Nazi regime will now be buried under a 12-meter-thick sarcophagus, just like the Chernobyl reactor but this time underwater.
Poison and torpedoes on board
Entombment is the only option to prevent the poison from damaging the environment. If the Norwegian parliament agrees to the Kystverket's suggestion, the work could begin "next summer at the earliest," Kjeras told SPIEGEL ONLINE. The burial can only be carried out in good weather conditions. The wreckage lies 150 meters below the surface and has to stay there. Experts have warned of the dangers involved in attempting to lift the U-864 -- and not just because of the toxic cargo. "We have to assume that there are still torpedos on board -- at least a couple," Kjeras told SPIEGEL ONLINE. "There is a far higher risk of one exploding during a salvage operation."
In fact there is a good chance that the World War II submarine is still armed. On Feb. 9, 1945, the ship -- an IX D2 model -- had been making its way back to Bergen because of engine trouble after having left the port just two days earlier. A British submarine, the HMS Venturer, then located the U-864 and sank it along with its 70-man crew.
It was an end to a secret mission that had been intended to take the brand new ship halfway around the world. The U-boat was heading for Japan and carried plans for the new Messerschmitt Me 262 jet fighters, along with engine parts from the Junkers and BMW factories. However, British intelligence codebreakers at Bletchley Park had already picked up on the so-called "Operation Caesar" and the Venturer was sent to track down the U-864.
A secret mission
Adolf Hitler's desperate plan was to send the submarine to break through the Allied blockade and equip the Japanese with the latest technology. The thinking was that if the Japanese could regain air superiority in the Pacific, then maybe the United States would have to send more troops to the Far East -- and relieve the pressure on the German forces in Europe.
The mercury that the U-864 had on board was intended to be used for weapons production. Now, almost 62 years after it sank, the German U-boat is the most threatening of about 2,500 wrecks that the Kystverket monitors in Norwegian waters. Around 400 of these are from World War II but up this is the first to require an underwater sarcophagus.
"This is a first for us," says Kjeras. According to a Kystverket study, around 30 of these kind of operations will have to be carried out over the next 20 years, in order to shut in all of the wreckages containing mercury. This method should provide "long-term protection for the environment."
The BBC recently interviewed Harry Plummer, a former "Venturer" seaman and an eyewitness to the German U-Boat's last moments. The Brits stalked the damaged submarine for three hours, as it zig-zagged through the Bergen fjord trying to escape them. Commander Jimmy Launders ordered four torpedoes to be fired but only the fourth one hit the target. At 12.14 p.m. the Venturer's logbook recorded a "loud, sharp explosion, followed by breaking-up noises." The U-864 broke in two and sank to the depths.
"It was a relief," says Plummer. But the next minute he and his buddies realized that a fellow submarine crew had been killed. "Afterwards you think to yourself: 'Poor bastards.'"