Seventeen Mile Cave is a lava tube located just that (17 miles), west of Idaho Falls. The cave itself is not seventeen miles long (thank goodness!). It’s probably more like 1/4 mile or 1/6 of a mile long. When we went to walk through it, there was another group there who mentioned that the cave used to be longer, but there was a portion that collapsed, making it impossible to go back farther. The cave reminded me a lot of the Civil Defense Caves near Rexburg, except this one was much more pleasant to walk through. The floor was almost entirely flat, making it super easy on the ankles. Walking through the cave, we found two pools that appeared to be pretty deep inside the cave.
As you climb into the cave, there’s a big blast of cold air that makes you wonder if you should enter or not. For me, I felt this was the coldest part of the entire cave. I’d definitely recommend a jacket, but once you get in the cave, you won’t feel too cold. The cave is mostly wide open the entire way through the cave and you cannot get lost in it. Adults are able to stand up fully, except for one very short portion of the cave where you’ll have to duck down slightly.
The cave is obviously a party spot for local High School students, as the cave is filled with lots of Graffiti and old alcohol bottles.
In the spring the cave can be wet from snow melt, so just be aware of that, and you may or may not want to bring some shoes that can get a little muddy. An occasional rattle snake or other critters have been spotted in the cave, but it’s rare.
Although the cave is located on private property, the owner has allowed the cave to be accessed by the general public. Just keep in mind that you are on private property when you go, and be respectful. As you’re driving along the highway, you won’t be able to see the cave, but you will see the sign indicating where the cave is.
17-Mile Cave is located only a few hundred feet to the south of U.S. Highway 20, about 17 miles west of downtown Idaho Falls, ID. You’ll know you hit the cave when you see the sign on the side of the road entitled “Elephant Hunters.” Park either at the sign along the highway, or you can pull off a little farther along the dirt road that circles the cave.
From Rexburg, hop on Highway 20 going west, and drive for about 45 minutes. It’s pretty easy to find.