The most dangerous cave in central Oregon

There is a cave just a few miles from Bend, that I feel is the most dangerous cave in central Oregon. Not because it’s the most likely cave to get killed in, like say by falling down a 100 foot pit. No, it’s dangerous because the cave is deceiving and can lure you in easily, when you may not have the faculty to get back out.

Thimble Cave is a very small, two-chambered spatter cone cave. It’s a part of the Horse Lava Tube System. It was named Thimble Cave because the cave is so small, you could metaphorically put the amount of cave passage it contains into a thimble.


Entrance to Thimble Cave


The photo above doesn’t show scale very well. That clump of grass is next to a foot and a half wide skylight that marks the only passable entrance into the cave. You drop down about 2 feet into a small bubble-like room filled with detritus. It’s pretty non-descript, except for the alluring hole in the floor along the southern wall.


The portal looking into the lower chamber.

It’s a small hole, much like the entrance. It’s about a foot and half in circumference. On my first exploration of the cave I was by myself. I saw this hole in the floor and peered in with my headlamp. It appeared to drop down almost 6 feet into a standing room chamber that I couldn’t quite see entirely from my vantage point in the upper chamber. It was risky, but I wanted to explore the room, so I stuck my feet in the hole and slowly slid down into the lower chamber.

The last bit into the lower chamber was a little sketchy because I had lowered myself as far as I could without letting go and still hadn’t touched the floor with my feet. But I knew I was definitely close, so I made the plunge. I let go and dropped perhaps several inches to the floor. It was spongy. Once I gathered myself, I inspected the room with my light and saw that the entire floor was composed of pine needles, pine cones, and dirt. A small pile of needles had accumulated underneath the portal to the upper chamber. I knew I was going to have some difficulties getting out, but I was going to wait for that until after I had explored the new room.

It was cozy, comfortable, and not terribly exciting. A small feeder tube that had closed shut during the formation of the cave showed signs of remelt, but aside from that, not much drew the eye, Well that is except for the couple of emaciated frogs on the floor. I found them alive but in very poor condition. Skinny from starvation because they had fallen into the cave and could not make their way back out. This was a sign of how dangerous this cave is, even for a monkey like me. I scooped up the tree frogs and went back to the portal and placed them up on the ledge so they could find their way out.

Now it was time to exit the cave. I initially made a non-serious attempt to climb out and see what type of handholds I had. Not much. It was a nearly vertical drop. It had just enough of a ledge for your chest to rest on, if only you could pull yourself up to it. My first attempt immediately showed me that I could not get out without a boost. I just didn’t have enough strength in my wrists and hands to pull myself out along the abrasive lava rock to get more leverage with my arms.

So I began to pile up a perch to stand on using what little was available to me. There was already a small pile of pine needles, so I reinforced it by placing more pine cones in it, and to my surprise, a couple of small buried rocks nearby. I piled them as high as they would go, maybe a foot tall. After having rested for a few short minutes, I made my attempt to escape. I stood atop the pile I had made and to my dismay they compressed and shrunk under my weight. I knew the longer I stayed on the pile, the less reach advantage I would have, so I immediately reached for a small handhold and heaved myself up as far as I would go. It wasn’t much of an advantage having that pile underneath me, but in retrospect, just enough. It gave me a few more inches to work with.

I was on the portal ledge struggling with my hand to find purchase, with my chest partially resting but not fully. It wasn’t like I could rest there and wait until I had more energy. I had to make a go of it now or I would have to drop back down and try again later but with less energy. I went for it. Pulling myself up inch by inch. It was an incredibly difficult task because my legs had no footholds whatsoever to help push me up making it an entirely upper body effort. To make matters worse, I was pulling my chest over a narrow, partially slanted slot that was abrasive and was catching on my light jacket.


A map to Thimble cave. Top part of the map shows the upper chamber with the two small skylights. The lower part shows the lower chamber and the 5 foot drop (squared) and the 5-foot ceiling height (circled).

After a couple minutes of greatly expended energy, I had managed to pull myself up just enough to allow my chest to rest in the narrow chute-like slot. My feet were still in the lower chamber dangling in open air, while my arms loosely held on to their holds. All the pressure was on my chest. Once I was rested, I scrambled to find more handholds but they were few. Sometimes only enough for a finger. It was piecemeal work maneuvering through the hole inch by very slow inch. The lava created a lot of friction against my jacket and I lost a button in the process. Eventually, I was able to pull myself out with great effort and plenty of well earned abrasions along my torso.

I must have been 26 when I explored that cave. In my top physical prime. A year or two later, I revisited the cave, because I had to survey it to draft a map. I knew I was in for a difficult time. However, this time I brought my 6 year old son who would remain on the surface by himself with my phone in case I had an emergency. I also packed in a couple of football-sized rocks to help me get out.

It was the same experience all over again. The rocks I had dragged in added very little to my reach because the ground kept compressing. Still, I managed to exit the lower chamber with yet more abrasions and a job well done.

A word of warning: I was in the best physical condition in my life when I entered that cave. I was also very skinny at a meager 150 pounds. Were I to try it today a little over a decade later, I would get stuck. I don’t nearly have as much energy as I once had. This cave, even among cavers is pretty much untouched. As far as I am aware, no one other than myself has explored it. If you are going in, chances are you may not be coming out. Those frogs are a dire warning to those would be explorers. If you go caving alone (which I don’t recommend), remember to leave a note detailing where you are going and when you will be back.


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