There , they discover an inner continent , which they name Symzonia after John Cleves Symmes , Jr .
In the story , Captain Seaborn leads a group of travelers into the concave inner surface of the Earth .
There , travelers discover an inner continent , which travelers name Symzonia after John Cleves Symmes , Jr .
In the story , Captain Seaborn leads a group of travelers into the concave inner surface of the Earth .