The naming of the cave comes from a story of two men who were caught in a bad storm. Upon hiking, these two guys were able to find the cave. One of them commented to the other, "This cave could hold about 40 horses." Another legend tells of a theif that hid 40 horses in the cave to avoid capture. Either way, there's no doubt that 40 horses would fit in the cave.

The hike up to the cave is steep. Elevation gain may only be about 100 feet but even the longest trail is still just under 500 feet (0.1 mile) to the cave. Once you find the trailhead, it's really easy to find. You'll just hike uphill until you come to a large opening in the mountain. The shorter trail has a lot more shale and is a pretty difficult scramble. The longer trail is still steep and difficult but there is much less shale.

Flashlights aren't required, as the cave is only about 50 feet deep. There are a few corners of the cave that are a little more fun to explore with a flashlight.

At the bottom of the trail is a culvert and when the water is higher, it's a fun place to splash around after the hike. You'll see a trail in the willows on the SouthEast side of the road near the culvert. If you follow that trail only about 100 feet of easy hiking, you'll find a smaller cave.

Seventeen Mile Cave is a lava tube, a cave created by the pocket in which lava used to flow and was left empty when the volcano became inactive. The cave gets its name from its location, just 17 miles outside of Idaho Falls. The entrance to the cave can be found a few hundred feet from the highway. The tunnel itself is a little less than ¼ mile long.

The floor of this cave is much smoother than most cave floors. The practically flat surface makes it easy to walk the length of the cave. The cave is not lit and, like most caves, is cool and humid throughout the year. Visitors should come to the cave prepared with flashlights and jackets.

The cave has one main tunnel that is easy to follow. There is no need to worry about getting lost. The end of the quarter mile trail is marked by two pools accompanied by a swampy area. It is difficult to get further than this area of the cave.  

Seventeen Mile Cave is a cave that receives a lot of traffic from the surrounding cities of Rexburg and Idaho Falls. This heavy traffic has caused the cave to have heavy graffiti covering most of its walls. Litter is also frequently found on the cave floor.

For those who live in Rexburg and Idaho Falls, Seventeen Mile Cave is easily accessible. This cave is easy to walk through and great for beginning spelunkers.