HSwMS Belos ( A214 ) HSwMS " Belos " is a submarine rescue ship in the Swedish Navy ' s 1st Submarine flotilla . She carries the Submarine Rescue Vehicle " URF " . She is also capable of carrying the NATO rescue system " NSRS " . HSwMS " Belos " is the largest ship ( by displacement ) in the Swedish Navy . History . Originally built as a diving support vessel , Belos ( III ) was launched in 1985 at the Dutch shipyard De Hoop operated in the international offshore business named “ Energy Supporter ” . In 1992 , she was purchased for the Royal Swedish Navy , was renamed Belos ( III ) , and has since been redesigned into an advanced diving and submarine rescue ship . A 214 , HSwMS Belos ( III ) , with the submarine rescue vessel URF was the first submarine rescue system that could perform Transfer Under Pressure ( TUP ) from a disabled submarine , via the rescue vessel to a decompression chamber system for treatment to avoid decompression sickness . Normally , the ship does not anchor , but hover at the distressed submarine using her Azimuth - and bow thrusters , and the Dynamic Positioning ( DP ) system . Onboard Belos , an extensive array of Remotely Operated Vehicles ( ROV ’ s ) , oceanographic equipment , craneage , diving - , medical - , and decompression facilities are accessible . Different sonar systems attached to the hull and towed astern of the Belos can be used for searching distressed submarines or other objects at the seabed . The Belos along with the Submarine Rescue Vessel ( SRV ) URF compose the backbone of the Swedish Submarine Escape and Rescue System . HSwMS Belos ( III ) can perform diving and underwater tasks using wet - bell and remotely operated underwater vehicles ( ROV ’ s ) . The ability to perform various types of underwater work is essential for submarine rescue operations . If the mating area to which the rescue vessel is to connect with the distressed submarine is covered by debris , fishing nets or other obstacles , these obstacles must be removed prior to mating the rescue vessel to the submarine . For smaller submarines or manned submersibles , the rescue operation may be cutting free the vessel itself if it is snagged by e . g . nets or cables and unable to surface ( see AS - 28 ) . The wet - bell is used for air - diving with two divers at a time to a maximum depth of 60 m . The divers are equipped with hot - water suits , TV - cameras , and constant communication to the diving supervisor on board the Belos . The underwater vehicles are all equipped with positioning systems , TV - cameras , and sonar systems , allowing them to operate in conditions of poor visibility . The maximum diving depth is 1000 m and underwater work is performed by using hydraulic manipulators with a range of interchangeable tools . The Belos ( III ) has a numerous craneage capacity . For lifting , craneage with a capacity of 5 , 6 , 10 och 100 tons is available . In addition , an A - frame in the stern with a capacity of 55 tons is used for handling the submarine rescue vessel URF . HSwMS Belos ( III ) , recent improvements : • Initially , the 100 t crane was used for launching and recovering the URF , a method rather unreliable during rough weather , leading to the construction and installation of the 55 t A - frame aft . • The decompression chamber system was improved leading to a decompression capacity of 40 at a time , including rescuees , medical personnel , and chamber attendants . The system consists of three cylinders divided into 4 main chambers . • Installation of TUP connection system ( maximally pressurised to the equivalent of 50 msw ) with direct access to the chamber system . • Co - operation with the Royal Navy resulted in the UK submarine Rescue Vessel LR - 5 was fully operational from HSwMS " Belos " including TUP capacity . This cooperation is now replaced with the NATO submarine Rescue System , NSRS which is fully operational from HSMS Belos . • Improvements of the Dynamic positioning ( DP ) – system , a system that using thrusters can hover in the sea at a fixed position .