Last September, Russia and Germany signed a deal to build a $5 billion gas pipeline running 1,200 kilometers under the Baltic from Vyborg near St. Petersburg to Greifswald on Germany's northeastern coast. The pipeline's projected route passes close to two of Tershkov's dumps, in the Gotland and Bornholm basins. Environmentalists in Russia and the Baltic states fear that construction could disturb the submerged and rusting shells and poison the sea. "It is very dangerous to build the pipeline in the Baltic," warns Alexei Yablokov of the Russian Center for Ecology Policy. "The sea bottom is entirely covered with bombs. We should, at the very least, first make a map of where they are."

In June 1947, Capt.-Lt. Konstantin Tershkov of the Soviet Navy had a serious problem on his hands. He'd been ordered to dump 34,000 metric tons of captured Nazi chemical weapons into the deepest part of the Baltic Sea by the end of the summer. Since most Soviet merchant and military ships in the Baltic were laden with loot from defeated Germany, Tershkov commanded only two small freighters rented from the British and two Soviet Navy trawlers, plus a crew of German civilians press-ganged into duty. "At this rate the job will take us 10 months," he wrote in his diary, frustrated by the distance to his appointed dumping ground in the Gotland Basin, between Sweden and Latvia. Instead, the resourceful Tershkov suggested a closer alternative: a patch of 100-meter-deep water just off the tiny island of Kristanso, east of the Danish island of Bornholm. By December, Tershkov's task was completed.

Almost 60 years later, his choice of a dumping ground is turning out to be a fateful one.