Bighorn-Horsethief Survey Project

Last Update: November 8, 2023


The Bighorn-Horsethief Cave system is one of the region’s most significant caves. Currently the system has been measured at 14.615 miles ( from past surveys. These surveys were completed in the 70’s and 80’s by various different of grottos and organizations. These past surveys were completed with analog instruments. Unfortunately a significant amount of data from past surveys has been lost. The current maps that are readily available have significant shortcomings of either generalizations or missing passages. The primary goal of this project is to remap the system with modern technology (DistoX2 laser rangefinders) and to create a complete map of the entire system. This will also be a chance to test out new LIDAR technologies.

This project is a fantastic opportunity for cavers of all experience levels to jump in and volunteer, whether you are new to caving and want to check out the longest cave system in Montana, or are an experienced surveyor and wish to keep your skills sharp. We plan to hold various training sessions to cover vertical technique, surveying instrumentation, sketching, conservation, and other caving skills.

Helpful Links

Join the email list to stay informed about upcoming survey trips and other project discussions!

Project Orientation Document – Standards and General Info

Our Google Drive folder has all of the project documents and information.

Learn more about how Cave Surveying works! (Don’t know how? We’ll train new folks on their first couple trips out with us!!)

Current Status

Bighorn Caverns

We are currently working with the National Park Service and the Apsáalooke (Crow) Indian Tribe to arrange access for the entirety of the re-survey. The re-mapping effort will not begin in Bighorn until access is approved.

Horsethief Cave

This resurvey project began back in March, 2021. We expect to host monthly survey trips, open to all members of the grotto and community.

Future Project Weekend Dates

Sign ups will be open about a month before the project weekend. The sign up link will be posted on the event listing for each project weekend here:

Donate to the Project

Project Leaders

The Northern Rocky Mountain Grotto of Montana is sponsoring this effort. Other local grottos are also encouraged to join in on this project.

Project Lead: Will Boekel
Cartography: Hans Bodenhamer
Data Processing and Storage: Jason Ballensky
Materials: Brian Gindling
Permitting: Jason Forberg & Ian Chechet
3D LiDAR Scanning: David Gianforte

Recent Project Trip Reports

Horsethief: Through the crack

Horsethief: Through the crack

My friend James asked me to take him on a more difficult caving trip. Horsethief was that weekend so I suggested we take a trip down to Wyoming. We left Bozeman about 2 then waited about an hour in Lovell for Colin who generously agreed to give us a ride ...
Horsethief: Trip 53: White Dirt Maze

Horsethief: Trip 53: White Dirt Maze

Trip 53: White Dirt As the second Horsethief Cave survey weekend of the season approached, Carl and I were eager to get up to Armpit. This would be our first Horsethief trip this season and it was looking like a great weekend to be in the area. We got out ...
Horsethief Cave: Cries of Glory: Horsethief Project Weekend

Horsethief Cave: Cries of Glory: Horsethief Project Weekend

September 16-18, Horsethief Project Weekend The group motto of the weekend was: “If you die, it probably isn’t worth it” We started our trip out to the Armpit early Friday morning amidst the forecast of looming rain. We wanted to avoid that if at all possible for a pleasant morning ...
Horsethief: An unusual Horsethief trip

Horsethief: An unusual Horsethief trip

I recently joined NRMG about a month ago and decided I wanted to go on the first posable trip. That ended up being the September horse thief resurvey weekend. I had things to commitments to into the evening on Friday so decided I would drive down from Bozeman morning of ...
Horsethief Cave: Horsethief Cave Survey Weekend May 20-22

Horsethief Cave: Horsethief Cave Survey Weekend May 20-22

If you’re not already familiar with Horsetheif Cave, it’s something like 20 miles long and likely not fully explored. A previous map exists but is incomplete and inaccurate. So, NRMG cavers and other cavers are undertaking a 7-10 year project to re-survey and fully explore the cave. This weekend yielded ...
Horsethief Cave: Did We Find the Pancakes Yet?

Horsethief Cave: Did We Find the Pancakes Yet?

After a long and mostly caveless winter I was excited for the March Bighorn/Horsethief Project weekend. Unfortunately, due to a lack of participation, the weekend was canceled. Upset and still wanting to go caving I contacted Will. He set me up with tasks and gave me the contacts of those ...
Horsethief Cave: Surveying for Pancakes (Horsethief Resurvey Project)

Horsethief Cave: Surveying for Pancakes (Horsethief Resurvey Project)

A truckload of southern Wyoming cavers including David Worthington, Isaac Lass, Ian Chechet and me, made the long trek up to Armpit City to join the monthly Bighorn/Horsethief Resurvey Project in October. We arrived late Friday evening after an adventurous time busting through some sloppy mud and snowdrifts, and dodging ...

All Trip Reports