Fishing and crabbing industries have been the mainstay of the economy of Unalaska island. The high-temperature geothermal resources study of volcanoes in Alaska has covered the geothermal areas in the summit caldera peak and also on the southeastern and eastern flanks of the Makushin. It is recorded as a subduction-related volcanic arc in the middle of the great Aleutian chain. Energy resources from the geothermal reservoir beneath the volcano have been assessed in a study carried out by the Alaska Power Authority to meet the power demands of the town of Unalaska and the Dutch Harbor. The study has established that such an energy generation from the geothermal resources would be cheaper than the diesel power system existing on the island. ORP Gryf (1936)  ORP "Gryf" (English: "Griffin") was a large Polish Navy minelayer, sunk during the 1939 German invasion of Poland. She was one of two large Polish ships that were not evacuated to Great Britain during Operation Peking prior to the outbreak of the Polish Defensive War ("Wicher" was the other). She was sunk in Hel harbour on 3 September 1939 during the opening stage of World War II. Built from 1934 at French shipyard Chantiers et Ateliers A. Normand in Le Havre, she was launched in 1936. Built after a genuine French project to Polish specifications, she was intended as a large minelayer with an armament close to that of a destroyer. Powered by two Sulzer "8SD48" engines of each, she was capable of 20 knots (37 km/h/23 mph), fast for its size. It also had quite a long range of roughly at 14 knots (26 km/h). As the Polish Navy was small and no other state expressed a need for such a vessel, she remained the only ship of that class. Prior to the outbreak of World War II she also served as a school ship and could take on board up to 60 additional students and NCOs. On 1 September 1939, with six minesweepers, "Gryf" left the naval base at Gdynia for the Operation Rurka, a failed attempt to lay a minefield at the entrances to the Gdańsk Bay. After taking aboard naval mines from a floating depot, the flotilla headed for Hel Peninsula, assisted by ORP "Wicher" and two gunboats. En route she was attacked by a squadron of 33 German Ju 87B dive bombers and damaged with several close misses.