Guantanamo Bay Naval Base.Guantanamo Bay Naval Base (Spanish: Base Naval de la Bahía de Guantánamo), officially known as Naval Station Guantanamo Bay or NSGB, (also called GTMO, pronounced Gitmo as jargon by members of the U.S. military[1]) is a United States military base located on 45 square miles (117 km2) of land and water on the shore of Guantánamo Bay at the southeastern end of Cuba. It ha..