The Mariana Islands (also the Marianas) are a crescent-shaped archipelago comprising the summits of fifteen mostly dormant volcanic mountains in the western North Pacific Ocean, between the 12th and 21st parallels north and along the 145th meridian east. They lie south-southeast of Japan, west-southwest of Hawaii, north of New Guinea and east of the Philippines, demarcating the Philippine Sea's eastern limit. They are found in the northern part of the western Oceanic sub-region of Micronesia, and are politically divided into two U.S. jurisdictions: the Commonwealth of the Northern Mariana Islands and, at the southern end of the chain, the territory of Guam.