Military diving is diving carried out by military personnel in the course of their duties. There are a number of different specialisations in military diving; some depend on the branch of the military. Offensive activities include underwater demolition, infiltration and sabotage, this being the type of work done by units such as the UK Special Boat Service or the United States Navy SEALs. Defensive activities are centered around countering the threat of enemy special forces and enemy anti-shipping measures, and typically involve defusing mines, searching for explosive devices attached to the hulls of ships, and locating enemy frogmen in the water.