The National Park Service describes Kenai Fjords National Park in Alaska as the location “where mountains, ice and ocean meet.” This description provides you with a good idea of what you can see at this national park if you choose to visit. And you ought to, since it’s just two hours’ drive away from Anchorage, a city easily reached by commercial flights from the Lower 48.

Visit Redwood National and State Parks in northern California and you can wander shaded forest trails lit by pale sunlight filtering through mist swirling around the crowns of tall trees while walking alongside forest floors carpeted by feathered fern fronds in varying shades of green. You’ll smell the forest scents and maybe a little salt air from the Pacific Ocean beyond.

Mammoth Cave National Park in Kentucky celebrates the world’s longest known cave system at over 426 miles (686 km), home to unique wildlife (eyeless fish and transparent cave shrimp), unique history (saltpetre mining and TB huts), and unique geology (karst topography, speleothems, and fossil sharks).

Bison, pronghorn, prairie dogs, and the third longest cave in the United States. You’ll find all this and more when you visit Wind Cave National Park in South Dakota, where there is as much to see and do above ground as there is below.