The Pool of Peace (or Lone Tree Crater) in Wijtschate is now a peaceful reminder of the great Mine Battle of June 1917. The opening of the offensive was marked by the detonation of 19 deep mines under the German lines between Ploegsteert and Hill 60. The explosions formed enormous craters in the landscape. The largest and most impressive crater is the Pool of Peace. It is 12 meters deep and has a diameter of 129 meters.