1. Great Smoky National Park
GSNP has more biodiversity than any region on earth outside the tropics. Key places to hit, all of which have easy access: Chimney Tops for panoramic views, Abram Falls, the Jump Off near Charlies Bunion, and the eerie abandoned logging town of Elkmont. There’s old-growth hemlock forest along the Trillium Gap Trail to the 25-foot-tall Grotto Falls.
The most unique feature of GSMNP happens for just a couple weeks each Spring when endemic species of synchronous fireflies illuminate the Appalachian forest by all glowing on and off simultaneously. There is also a rare species of firefly that glows electric blue.