Given the question: Information: - TheMediterranean Sea (pronounced ) is a sea connected to the Atlantic Ocean, surrounded by the Mediterranean Basin and almost completely enclosed by land: on the north by Southern Europe and Anatolia, on the south by North Africa, and on the east by the Levant. The sea is sometimes considered a part of the Atlantic Ocean, although it is usually identified as a separate body of water. - A mid-ocean ridge is an underwater mountain system formed by plate tectonics. It consists of various mountains linked in chains, typically having a valley known as a rift running along its spine. This type of oceanic mountain ridge is characteristic of what is known as an oceanic spreading center, which is responsible for seafloor spreading. The production of new seafloor results from mantle upwelling in response to plate spreading; this isentropic upwelling solid mantle material eventually exceeds the solidus and melts. The buoyant melt rises as magma at a linear weakness in the oceanic crust, and emerges as lava, creating new crust upon cooling. A mid-ocean ridge demarcates the boundary between two tectonic plates, and consequently is termed a divergent plate boundary. - Submarine volcanoes are underwater vents or fissures in the Earth's surface from which magma can erupt. A large number of submarine volcanoes are located near areas of tectonic plate movement, known as mid-ocean ridges. The volcanoes at mid-ocean ridges alone are estimated to account for 75% of the magma output on Earth. Although most submarine volcanoes are located in the depths of seas and oceans, some also exist in shallow water, and these can discharge material into the atmosphere during an eruption. The total number of submarine volcanoes is estimated to be over 1 million, of which some 75000 rise more than 1km above the seabed. - Sicily is the largest island in the Mediterranean Sea. It constitutes an autonomous Region of Italy, along with surrounding minor islands, officially referred to as "Regione Siciliana" (in Italian, Sicilian Region). - Campi Flegrei del Mar di Sicilia is a field of submarine volcanoes located south - west of Sicily . It includes the vent of Ferdinandea , otherwise known as Graham Island , which erupted and emerged above sea level in 1831 , and encompasses a larger volcano known as Empedocles . The last recorded eruption was in 1867 , from a vent named Pinne . There was mild seismic unrest at Ferdinandea in 2000 - 2002 . At its highest , Campi Flegrei comes to 8 meters ( 26 feet ) below sea level . Given the information, choose the subject and object entities that have the relation of 'instance of'.
The answer is:
campi flegrei mar sicilia , mountain