The demands of working for one of America's biggest commercial diving companies, US Underwater Services. The work involves cleaning and repairing water towers, sewerage systems and offshore oil rigs, and brings with it a variety of dangers, including the risk of internal injuries such as embolisms, thrombosis and decompression sickness. New trainee 19-year-old Matt Donaldson is given his first job of inspecting a 130ft water tower for cracks.
