The Paardenmarkt bank is a sandbank in the North Sea some 300 to 1500 meters from the Belgian coast near Knokke-Heist and close to the port of Zeebrugge.
[1] After the First World War, from November 1919 to May 1920 some 35,000 tons of ammunition- of which some 10,000 tons were mostly German chemical ammunition (mustard gas)- was dumped by the Belgian authorities at the bank.
[2][3] In 2013 after searching the government archives, scientists disputed the number as an underassessment and claimed that probably all 35,000 tons of the dumped munitions are chemical munitions, because after the war conventional munitions were usually disposed of by exploding them under controlled circumstances.
Due to the high financial cost and for safety reasons the Belgian government has decided not to clear the area and practices a "don't touch" policy.
The site is however marked with buoys and is constantly monitored, and is a prohibited area for fishery activity and for anchoring.