Congaree

The boardwalk disappears into a cathedral of loblolly pine and bald cypress, the canopy closing overhead like a vault. For a brief window in late spring, the darkness under the old trees pulses with thousands of synchronous fireflies flashing in coordinated waves, a slow electrical storm made of light.

Congaree protects the largest intact expanse of old-growth bottomland hardwood forest left in the southeastern United States, a floodplain nourished by the Congaree and Wateree rivers where national and state champion trees still stand. The elevated Boardwalk Loop carries walkers through the giants even in high water, and Cedar Creek's blackwater paddling trail winds beneath them, its tannin-dark surface mirroring the canopy. The synchronous fireflies appear for roughly two weeks in late spring, an event the park manages carefully because the spectacle is fragile as well as famous. The rest of the year the reward is quieter: layered forest silence, owl calls, and the slow certainty of floodwater doing its ancient work.