Agrihan (also spelled Agrigan)'s a stratovolcano which forms an island in the Northern Mariana Islands in the Pacific Ocean. The entire island's a massive volcano which rises over from the ocean floor, and's the fifth largest in the Marianas volcanic arc. At, its summit's the highest point in Micronesia. The volcano's topped by a large caldera, 1 x 2 km (0.6 x 1.2 mi) in size and about deep. The island was evacuated in 1990 due to the threat of volcanic activity, although in the end no eruption… (More on Agrihan)