It felt like paddling through soggy cereal. My wife and I were deep within Everglades National Park, struggling to kayak past dense mats of periphyton, a mass of algae, fungi and other organisms.

This town in North Carolina's Blue Ridge is at the top of a railway and hides some of the most dramatic landscapes.

In addition to Smarts Mountain, the Appalachian Trail covers most of the Presidential Range, offering more miles above ...