A wildfire which has scorched 76 square miles near the Georgia-Florida state line could keep burning for the next six months, officials said.
The fire was sparked by lightning on April 6 inside the Okefenokee National Wildlife Refuge.
It grew by 76% over the weekend as winds pushed flames deeper into areas of the swamp parched by drought.
Susan Granbery of the Georgia Forestry Commission said there was no immediate threat to communities outside the vast refuge.
More than 430 firefighters and support personnel are working to contain the fire.
Ms Granbery said only a big rainstorm will be able to extinguish the blaze, and forecasters predict that may not happen until November.
A 2011 wildfire inside the refuge burned for a full year.