Spelunking in Carlsbad Caverns National Park

Carlsbad Caverns is famous for the beauty and breadth of its inky depths, as well as for the accessibility of some of its largest caves. All cave tours are ranger led, so safety is rarely an issue in the caves, no matter how remote. There are no other tour guides in the area, nor is there an equipment retailer other than the Wal-Mart located in Carlsbad, 23 mi away. Depending on the difficulty of your cave selection (Spider Cave is the hardest to navigate), you'll need at most knee pads, flashlight batteries, sturdy pants, hiking boots with ankle support, and some water.

Hall of the White Giant. Plan to squirm through some tight passages for long distances to access a very remote chamber, where you'll see towering, glistening white formations that explain the name. This strenuous, ranger-led tour lasts about four hours. Steep drop-offs might elate you—or make you queasy. Wear sturdy hiking shoes and bring four AA batteries with you. Visitors must be at least 12 years old. At the visitor center, Carlsbad Caverns National Park, NM, 88220. 877/444-6777. $20. Reservations essential. Tour Sat. at 1.

King's Palace. Throughout King's Palace, you'll see leggy "soda straws" large enough for a giant to sip and multi-tiered curtains of stone—sometimes by the light of just a few flashlights. The mile-long walk is on a paved trail, but there's one very steep hill. This ranger-guided tour lasts about 1½ hours and gives you the chance to experience a blackout, when all lights are extinguished. While advance reservations are highly recommended, this is the one tour you might be able to sign up for on the spot. Children younger than 4 aren't allowed on this tour. At the visitor center, Carlsbad Caverns National Park, NM, 88220. 877/444-6777. $8. Tours late May-early Sept., daily 10, 11, 2, and 3; early Sept.-late May, daily 10 and 2.

Left Hand Tunnel. Lantern light illuminates the easy walk on this detour in the main Carlsbad Cavern, which leads to Permian Age fossils—indicating that these caves were hollowed from the Permian Reef that still underlies the Guadalupe Mountain range above. The guided tour over a packed, dirt trail lasts about two hours. It's a moderate trek that older kids can easily negotiate, but children under 6 aren't allowed. At the visitor center, Carlsbad Caverns National Park, NM, 88220. 877/444-6777. $8. Tour daily at 9.

Lower Cave. Fifty-foot vertical ladders and a dirt path lead you into undeveloped portions of Carlsbad Caverns. It takes about half a day to negotiate this moderately strenuous side trip led by a knowledgeable ranger. Children younger than 12 are not allowed on this tour. At the visitor center, Carlsbad Caverns National Park, NM, 88220. 877/444-6777. $20. Reservations essential. Tour weekdays at 1.

Slaughter Canyon Cave. Discovered in the 1930s by a local goatherd, this cave is one of the most popular secondary sites in the park, about 23 mi southwest of the main Carlsbad Caverns and visitor center. Both the hike to the cave mouth and the tour will take about half a day, but it's worth it to view the deep cavern darkness as it's punctuated only by flashlights and, sometimes, headlamps. From the Slaughter Canyon parking area, give yourself 45 minutes to make the steep ½-mi climb up a trail leading to the mouth of the cave. Arrange to be there a quarter of an hour earlier than the appointed time. You'll find that the cave consists primarily of a single corridor, 1,140 feet long, with numerous side passages.

You can take some worthwhile pictures of this cave. Wear hiking shoes with ankle support, and carry plenty of water. You're also expected to bring your own reliable two-D-cell flashlight. Children younger than 6 are not permitted. It's a great adventure if you're in shape and love caving. End of Hwy. 418, 10 mi west of U.S. 62/180, Carlsbad Caverns National Park, NM, 88220. 877/444-6777. $15. Reservations essential. Tours Memorial Day-Labor Day, Fri., Sat., and Sun. at 10; rest of the year, weekends at 10.

Spider Cave. Visitors may not expect to have an adventure in a cavern system as developed and well stocked as Carlsbad Caverns, but serious cavers and energetic types have the chance to clamber up tight tunnels, stoop under overhangs, and climb up steep, rocky pitches. This backcountry cave is listed as "wild," a clue that you might need a similar nature to attempt a visit. Plan to wear your warm, but least-favorite clothes, as they'll probably get streaked with grime. You'll also need soft knee pads, 4 AA batteries, leather gloves, and water. The gloves and pads are to protect you on long, craggy clambers and the batteries are for your flashlight. It will take you half a day to complete this ranger-led tour noted for its adventure. Visitors must be at least 12 years old and absolutely not claustrophobic. Meet at visitor center, Carlsbad Caverns National Park, NM, 88220. 877/444-6777. $20. Reservations essential. Tour Sun. at 1.

Expeditions

Ranger-led Tours. Cavers who wish to explore both developed and wild caves can go on Ranger-led Tours. Reservations for the six different tours, which include the Hall of the White Giant and Spider Cave, known for its tight twists and grimy climbs, are required at least a day in advance. Payment is by credit card over the phone or online (or by mailing in a check, if you're making reservations 21 days or more in advance; but confirm first that space is available). 877/444-6777.

Cave Resources Office. Those who want to go it alone outside the more established caverns can get permits and information about 10 backcountry caves from the Cave Resources Office. Heed rangers' advice for these remote, undeveloped, nearly unexplored caves. 575/785-2232.