This 1840s illustration shows a lady from the island of Guam. Guam is a U.S. island territory in Micronesia, in the Western Pacific. Guam is part of the area of the world known as Oceania. Oceania is a geographic region that includes Australasia, Melanesia, Micronesia and Polynesia. Spanning the Eastern and Western Hemispheres, Oceania has a land area of 8,525,989 square kilometers.