The largest vessel in the Swedish Navy, BELOS arrived on the Clyde to take part in submarine rescue trials together with the Norwegian Coastguard ship BARENTSHAV that had arrived a few days previously. BELOS had begun her career as a commercial offshore supply ship ENERGY SUPPORTER, and was built by the De Hoop shipyard at Lobith in Holland in 1985. She was later acquired by the Swedish Navy and converted at Rio de Janeiro to become a submarine rescue and salvage ship, and was formally commissioned in October 1992. She has twin aximuth thrusters mounted aft, electrically driven, and three bow thrusters, giving her exceptional manoeuvrability. At 104.9 metres in length, BELOS is fitted with a helicopter deck forward, and carries an extensive array of diving equipment as well as various submersible craft.