Most of us go out of our way to avoid a "fiery furnace" situation, but many visitors to Arches National Park are the exception. Ranger-guided hikes into the park's version of the Fiery Furnace often fill in advance, so the park is experimenting with online reservations through the end of October.

A place named the Fiery Furnace certainly sounds intriguing, if not necessarily inviting, so what's the attraction? A park publication offers some details about the location, and why you need a reservation to go there:

The Fiery Furnace offers a labyrinth of narrow passageways and abrupt dead-ends among a series of sandstone fins. Though it does not encompass a very large area, it is easy to become disoriented or lost. For this reason, and to protect native plants and soils, visitors must join a guided hike, or obtain a special permit, in order to enter the Fiery Furnace.

Ranger-guided hikes through the Fiery Furnace are offered twice each day from March through October. These popular three hour hikes are considered by most to be moderately strenuous. The Fiery Furnace hike is not a casual stroll and everyone attending the walk should be aware of the nature of this hike and be properly equipped.

This sounds like an interesting hike, but it's clearly not for everyone.

During the hike, participants will be walking and climbing on irregular and broken sandstone, along narrow ledges above drop-offs and in loose, sometimes wet, sand. There are cracks which must be stepped over and narrow places in the rock that you must squeeze into and pull yourself up and through. In some of these places, you must hold yourself off the ground by pushing against the sandstone walls with your hands and feet.

Due to the maze-like nature of the terrain, all participants are committed to completing the hike once they enter the Fiery Furnace.

All participants must wear good hiking shoes or boots that have gripping soles. No sandals or high heeled shoes are allowed. Solid ankle support and good sole tread are recommended.

Each person must carry at least one quart or liter of water and a backpack to carry the water and other gear so that their hands are free to be used to navigate the terrain.

Due to the tour's difficulty and length it is not recommended for children under five years of age. One adult is required for each child age six or under attending the tour. One adult is recommended for each child age seven to twelve. Parents must closely supervise children at all times during the tour.

Think you might be interested, but you're not quite sure? You can view some photos taken during one of the tours to get a virtual preview.

So, what's the deal about reservations online?

Due to their popularity, these hikes often fill in advance, so the park is experimenting from now through the end of October with the option for visitors to make reservations online. It's hoped this system will avoid disappointment for visitors who have made a long trip to the area, only to find all of the spaces on a guided hike already taken. Once the trial period is over, the park will evaluate the online option and decide whether or not to continue it.

Reservations may also be made in person at the visitor center, but only up to seven days in advance. Space on the walks is limited and groups of more than 15 people should split up and go on separate walks or check with the park well in advance to request a special tour. Special tours are contingent upon the availability of staff to lead the hike.

Fees for the tour are $10 for adults; $5 for children 7 to 12 years old as well as Interagency Senior Pass and Interagency Access pass holders. Kids up to 6 years old are free.

If you'd like to make this hike without a ranger, you must obtain a permit at the park visitor center. A fee is charged, and everyone in the group obtaining the permit is required to watch a five-minute video covering visitor safety and resource concerns. Permits can be obtained up to seven days in advance at the visitor center.

If you're not well-schooled on the ins and outs of the Fiery Furnace, the park highly recommends you take the ranger-guided walk, or make this hike with someone who very familiar with the route. A park spokesman described it as "a cave without a roof," and it's very easy to become confused in the maze of passageways.

This popular hike sounds like an interesting and unusual experience for those who know what to expect—and who are prepared for the moderate physical demands of the trip.

You'll find additional information about Arches National Park and the Fiery Furnace on the park website.