California's geographical diversity is by far its greatest asset. It's rare that in one state you can hit up the beach, hike mountains, explore dense forests and wander through the desert.

the national park with perhaps the most complicated logistics in the country. The small chain of five islands sits 10 to 60 miles off the Southern California coast, requiring hourslong boat rides ...

Airports: Redding and Chico, California; Reno ... and plug dome—can be found in Lassen Volcanic National Park, where they literally bubble and steam.

There are a series of hikes in the Giant Forest, ranging from short one-hour jaunts to daylong treks; the National Park Service lists a few on its website. Visitors recommend longer hikes ...