Trials have been carried out in order to investigate the possibilities to quench fire in under water explosives. Two types of explosives in small and medium scale have been studied, a TNT/RDX/Al explosive and PBX with AP/RDX/HTPB/Al. Two methods to extinguish fire have been studied, water sprinkling and dumping into water. The trials show that TNT/RDX/AL is easily extinguished by both methods, but have to get started quickly due to risks for rapid fire escalation. It is far more difficult to extinguish a fire in PBX. This trial shows that sprinkling is not a possible method. Dumping a burning PBX charge is a working method. A continued reaction in water was noticed but it ends very quickly. Fire in ammunition onboard a ship is estimated to be possible under certain conditions in case the explosive is a TNT/RDX/Al type. An underwater PBX can exclusively be extinguished by being dumped into water automatically.