Actun Tunichil Muknal is a sacred Mayan ceremonial cave. It translates as "Cave of the Stone Sepulchre," and there is a reason for this name... but more on that later.

The cave was discovered in the mid 1980s by an archaeologist who was shell-shocked by the number of artifacts and human remains within. It was explored, mapped, catalogued, and 98% of the artifacts are still inside. The cave, in terms of natural beauty, puts any American cave to shame, and I'm a caver by hobby, so I can say that! This, combined with the high adventure facet and the Mayan artifacts, makes this a priceless epic trip, the likes of which I really have yet to encounter on any of the 7 continents.

Because of its delicate natural and historic beauty, only two San Ignacio guide companies are authorized to lead trips into ATM: Pacz Tours (headquartered in Eva's Restaurant and the most recommended) and Mayawalk Tours (across the street from Eva's, more expensive and not as good). If you book with Pacz, try to get Juan Carlos as your guide. He's the best. Tours are $65 in the low season if you pay in cash with Pacz and $75 in the high season, including transportation and lunch.

There's an hour of driving to reach the cave through the beautiful Roaring River Valley, where the Progressive Mennonites produce almost 80% of Belize's agriculture.

Then you enter the archaeological park, which protects Actun Tunichil Muknal, and your hike begins.

It's a mile and a half to the cave, and you'll cross the Roaring River on foot three times. You'll likely see some wildlife, often the deadly Fer de Lance snake. If you're lucky, your guide will let you taste termites (they taste like carrots!), wild limes, pineapples, and habanero peppers on the way.

At the cave entrance you'll eat lunch and swim in the deep, clear pool. Then the trip begins.

You'll thrash upstream for an hour, sometimes in cold water up to your shoulders, through narrow cracks and up small waterfalls. Sometimes your guide may have you turn off your light, and the group will proceed hand in hand in total darkness. Exciting and scary!

Then you'll scramble up a cliff, remove your shoes, and enter the ceremonial level of the cave where there are hundreds of pots and human sacrificial remains. This section of the cave is profusely decorated as well.

The climax of the cave is a visit to the its namesake, a tiny chamber that hides an entire human skeleton, coated in calcite crystals. It's breathtaking and quite creepy.

The government is considering closing ATM for lots of reasons. It's dangerous. It's delicate. So go now while you still can!

More photos in "How To Do Belize."