Your first stop should be Kilauea Visitor Center, a rustic structure in a shady grove of trees just inside the entrance to the park. Here, you can get up-to-the-minute reports on the volcano's activity, learn how volcanoes work, see a film showing blasts from the past, get information on hiking and camping, and pick up the obligatory postcards.
Filled with a new understanding of vulcanology and the volcano goddess, Pele, you should then walk across the street to Volcano House; go through the lobby and out the other side, where you can have a good look at Kilauea Caldera, a 2 1/2-mile-wide, 500-foot-deep pit. The caldera used to be a bubbling pit of fountaining lava; today you can still see wisps of steam that could, while you're standing there, turn into something more.
Now get out on the highway and drive by the Sulphur Banks, which smell like rotten eggs, and the Steam Vents, where trails of smoke, once molten lava, rise from within the inner reaches of the earth. This is one of the few places where you feel that the volcano is really alive. Stop at the Thomas A. Jaggar Museum (open daily 8:30am to 5pm; free admission) for a good look at Halemaumau Crater, which is a half-mile across and 1,000 feet deep, and (maybe) Mauna Loa, 20 miles to the west. The museum shows eruption videos, explains the Pele legend in murals, and monitors earthquakes (a precursor of eruptions) on a seismograph, recording every twitch in the earth.
Once you've seen the museum, drive around the caldera to the other side, park, and take the short walk to Halemaumau Crater's edge, past stinky sulfur banks and steam vents, to stand at the overlook and stare in awe at this once-fuming and bubbling old firepit, which still generates ferocious heat out of vestigial vents.
If you feel the need to cool off now, go to the Thurston Lava Tube, the coolest place in the park. You'll hike down into a natural bowl in the earth, a forest preserve the lava didn't touch--full of native bird songs and giant tree ferns. Then you'll see a black hole in the earth; step in. It's all drippy and cool here, with bare roots hanging down. You can either resurface into the bright daylight or, if you have a flashlight, poke on deeper into the tube, which goes for another quarter-mile or so.
If you're still game for a good hike, try Kilauea Iki Crater, a 4-mile, 2-hour hike across the floor of the crater, which became a bubbling pool of lava in 1959 and sent fountains of lava 1,900 feet in the air, completely devastating a nearby ohia forest and leaving another popular hike, ominously known as Devastation Trail. This half-mile walk is a startling look at the powers of a volcanic eruption on the environment.
For a glimpse of ancient Hawaiian art, check out the Puu Loa Petroglyphs, around the 15-mile marker on Chain of Craters Road. Look for the stack of rocks on the road to park. A brief, half-mile walk from the road will bring you to a circular boardwalk where you can see the thousands of mysterious Hawaiian petroglyphs, carved in stone. This area, Puu Loa, was a sacred place for generations; fathers came here to bury their newborn's umbilical cord in the numerous small holes in the lava, thus ensuring a long life for the child. A word of warning: It's very easy to destroy these ancient works of art. Do not leave the boardwalk, and don't walk on or around the petroglyphs. Rubbings of petroglyphs will destroy them; the best way to capture the petroglyphs is with a photo.
Note: This information was accurate when it was published, but can change without notice. Please be sure to confirm all rates and details directly with the companies in question before planning your trip.