On August 18, ALROSA’s mine surveyors dropped a special buoy from the helicopter to the bottom of Mir open pit mine to monitor water level in the dark. The LED-buoy is equipped with a battery and a light-reflecting prism.

Mine surveyors measure the volume of water accumulated in the open pit mine. The obtained data allow estimating volumes of accumulated water and predicting the level of threat for miners and rescuers who are working underground.