St. Marys is a city in Camden County, Georgia, United States, located on the southern border of Camden County on the St. Marys River in the state's Low Country. The Florida border is just to the south across the river, Cumberland Island National Seashore is to the northeast, and Kingsland, Georgia, is to the west. Jacksonville, Florida, is 38 miles south, and Savannah, Georgia, is 110 miles north. The city is home to the National Seashore's visitor center and boat access; the St. Marys Submarine Museum, and Crooked River State Park. It is bordered by Kings Bay Naval Submarine Base, home port for several . The city hosts the annual St. Marys Rock Shrimp Festival. The area was first explored in the mid-16th century by Spanish expeditions as part of the settlement of Spanish Florida. Through the decades it also came under the colonial influence of Great Britain and finally the United States. By the 2020 census, the city had a population of 18,256. Geography St. Marys is located along the southern border of Camden County on the north bank of the St. Marys River. The state of Florida is to the south, across the river. The city of Kingsland borders St. Marys to the west. According to the United States Census Bureau, St. Marys has a total area of , of which is land and , or 9.57%, is water. Climate St. Marys has a humid subtropical climate (Cfa) with long, hot summers and short, mild winters. History The St. Marys river area was first explored by Spanish expeditions in the mid 16th century as part of the settlement of Spanish Florida, with nearby St. Augustine as the established capital. The original Spanish settlement was founded in 1566, making this the second-oldest continuously inhabited European-established settlement in the what became contiguous United States. Settlement for colonial Georgians became legal after the Treaty of Paris in 1763, when Britain exchanged some territory with Spain after defeating France in the Seven Years War. Following independence in the American Revolutionary War, local inhabitants of Camden County gathered on Cumberland Island and signed a charter for "a town on the St. Marys" on November 20, 1787. There were twenty charter members, who each received four town lots and one marsh lot (outside the boundary of the town on the east side in the marshes); each lot was square, with the total town area