The German submarine U-864 was torpedoed by the British submarine Venturer on February 9, 1945 and sunk approximately two nautical miles west of the island Fedje in Hordaland. U-864 was carrying about 67 metric tonnes of metallic mercury that implies a threat to the marine environment.
In September 2007 The Norwegian Costal Administration commissioned Det Norske Veritas to further investigate different alternatives to salvage the wreck and remove the mercury from the seabed.
The objective of this supplementary study is to propose a survey method, or combination of methods, that will give the best probability of detecting sub-bottom mercury canisters around the wreck of U-864.
DNV’s overall conclusion is: A combination of single caesium vapour magnetometer and pipetracker, positioned by acoustic LBL technique, is the preferred method to locate sub-bottom canisters.
The searching will take at least six days and all surface debris must be cleared from the site prior to operation.