We have used non-explosive demolition agent Dynacem to break up submerged rocks located underwater, on the bottom of a pond. We drilled the hole diameter 38 mm. We have put Dynacem mix in an underwater hole in granite rock that was full of water initially. We used a garden hose fixed to a coke bottle, and were pouring Dynacem mix into the bottom of the hole, so the mix was displacing water and filling the hole. We did not expect that it would crack, but the crack formed after 19 hours and it was 2 cm wide after another 4 hours. Water temperature was 11,5 deg C, air temperature 2,5 deg C. Using exactly the same method we removed several underwater rocks.