A large sinkhole opened up in a field in Belgium at the weekend, possibly the result underground tunnels dug more than 100 years ago during WWI.<br /><br />The sinkhole, which measures five metres across, was found in a muddy field in Ypres, where three of the bloodiest battles of WWI were fought in 1914,1915 and 1917.<br /><br />According to the filmer, networks of hidden tunnels and trenches still exist in this area and may have caused the ground to give way here, creating the sink hole.
