Underwater demolition

[3]: 9  In addition, a Corporal Jones made the first emergency swimming ascent after his air line became tangled and he had to cut it free.

[citation needed] The early diving helmets used had no non-return valves, which meant that if a hose was severed near the surface, the high-pressure air around the diver's head rapidly evacuated the helmet, causing a large pressure difference between the surrounding water and the remaining gas, with extreme and sometimes life-threatening effects.

At the British Association for the Advancement of Science meeting in 1842, Sir John Richardson described the diving apparatus and treatment of diver Roderick Cameron following an injury that occurred on 14 October 1841 during the salvage operations.

[5] On an occasion that year the Royal Engineers set off a huge controlled explosion which shattered windows as far away as Portsmouth and Gosport.

Shortly after the American Civil War, Brevet Maj. Gen. John G. Foster, a West Point trained engineer, became one of the first acknowledged experts in underwater demolition.

After joining OSS, he was vital in establishing the first cadres of U.S. military operational combat swimmers during late World War II.

[14][15] Expanding grout is a cement that expands on curing, producing extremely high pressure, in the order of 18,000 pounds per square inch (120 MPa) when confined in a hole drilled in a brittle material such as concrete or rock, causing it to crack without large movements, noise, dust or major shock waves.

14 The usual methods for underwater wrecking in place are manual flame cutting by divers and surface workers, mechanical demolition using heavy lift cranes, explosive sectioning, dispersal, or flattening, and burial or settling by hydraulic dredging.[16]: Ch.