Expeditionary Warfare, Littoral Operations, Rapid Environmental Assessment (REA) – whatever term is employed a knowledge of the environment is critical to military success. Today, battlespace characterisation is an assessment activity with direct operational relevance for each of the Services. It is important to the planning and conduct of joint operations generally, and land and naval operations in particular. Knowing where ships can navigate safely, where amphibious landings can be conducted and how systems, weapons and sensors will be affected by prevailing environmental conditions - is a fundamental enabler for successful operations. In particular, environmental information in the littoral battlespace can be used to gain tactical advantage in amphibious operations, mine warfare and special operations missions.