There was a significant maroon settlement in the Great Dismal Swamp. It was largely abandoned and assimilated after the civil war - without the threat of slavery, there wasn't much reason to be living there, and much of the swamp was drained for logging and farmland.
It's worth pointing out that fugitive slave settlements are the sort of thing that doesn't get recorded well by historians or by archeological evidence. The people taking notes are often the slave owners, not the slaves, and even more permanent settlements could easily be swallowed by the swamp, as happened to Jamestown fort until its rediscovery in 1994.
/u/better-off-read has previously answered Did slaves ever seek refuge with Native Americans?