Normally, firefly swamps are small, and secluded, and in a clearing.
Indeed, this is a swamp, every part of it is covered with a tree, but it is not small.
The trees grew like long towers with vast canopies on small mounds distributed across the swamp.
They have fluorescent carnivorous plants at their bases in a ring, like fairy rings.
They could see they are carnivorous plants only because of the fireflies stuck on them.
However, the swamp went on and on like a snake, between big mounds, small mounds and it was closed in by tall sheer vertical cliffs that are clearly eagle mountains.
Looking at it, one can clearly tell which part is the desert mountain, and where eagle mountains begin, but that's not the point.
They were in the only small pebble beach which is high enough to see the entire ocean of fireflies.
It's like they are standing in the starry sky.