St Marys is the gateway to Cumberland Island, Georgia's largest and southernmost barrier island. Pristine maritime forests, undeveloped beaches, and wide marshes preserve the stories of both man and nature. Natives, missionaries, enslaved African Americans, and wealthy industrialists all walked here. Cumberland Island is also home to more than 9,800 acres of congressionally designated wilderness. Its climate is hot and humid during summer, when temperatures tend to be in the 80s, and mild during winter, when temperatures tend to be in the 60s. The warmest month is July, with an average high of 90 degrees F, while the coldest is January, with an average low of 45 degrees F.