Down at the bottom of Switzerland's deepest lake is one of the country's murkiest secrets. For here is disturbing evidence of Switzerland's little-known Second World War defence effort. It poses a potentially devastating threat to the Alpine nation, 70 years after the conflict.


The placid waters of Lake Thun spread out for 11 miles beneath Faulensee village. Some 700 feet beneath the surface more than 9,000 tons of Swiss army munitions lie dumped on its watery floor. The ordnance includes artillery shells, hand grenades, and explosives that were meant to defend Switzerland against a Nazi invasion that never happened. After the war, the army began a 20-year process of getting rid of its vast munitions stockpile by dumping most of it into four Alpine lakes, all of which are used to supply drinking water to the surrounding population. Lake Thun, in the central Swiss canton of Bern, took the brunt of the disposal programme, which ended in 1964.