A Submarine Escape Training Tower is a facility used for training submariners in methods of emergency escape from a disabled submarine underwater. It is a deep tank filled with water with at least one underwater entrance at depth simulating an airlock in a submarine. Since the 1930s, towers have been built for use by the Royal Navy, US Navy, Royal Australian Navy and in several other countries. Royal Navy SETT The Submarine Escape Training Tank (SETT) is a deep facility primarily operated to conduct training with submarine escape equipment, operated by the Royal Navy. The facility, located at Fort Blockhouse, Gosport opposite HMNB Portsmouth, includes a fresh, chlorinated water column with a single escape chamber (as fitted to some classes of RN submarines) mounted at the base, through which students can conduct a fully representative escape cycle from , closely replicating actions which would be required if forced to abandon a distressed submarine from depth. The SETT has its own dedicated boiler house to maintain its water temperature at 34 °C (94 °F). The SETT was commissioned in 1954, with the first students trained in July of that year. Since that time completion of ‘the Tank’ has been a rite of passage for all RN Submariners. Training includes ascents from increasing depths as a major element, but in addition is underpinned by lectures and practical training in how to survive within a disabled submarine, operation of emergency equipment and survival techniques on reaching the surface – a package of potentially life saving skills. Over the years, the SETT has been used to train submariners from Italy, USA, Greece, Canada, Israel, Russia, Venezuela, Turkey, Australia and the Netherlands – with the staff and facility enjoying a worldwide reputation for excellence and good practice. Owing to a combination of increased safety associated with modern submarine design, submarines operating in areas where escape would be impossible with current equipment and the risks associated with the conduct of training, the RN discontinued pressurised submarine escape training in March 2009. The staff at SETT are drawn from the ranks of the UK Submarine Service. All members of SETT staff form part of the SMERAT (Submarine Escape and Rescue Advisory Team), some members form the UK SPAG (Submarine Parachute Assistance Group), and some form part of the UK contribution to the NSRS (LR5) Team. All staff are trained in advanced life-saving techniques and diving medicine. Other