Last Update: May 7, 2025

Overview

The Bighorn-Horsethief Cave system is one of the region’s most significant caves. Currently the system has been measured at 14.615 miles (caverbob.com) 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

This survey 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: https://nrmg.org/events/
2025 Project Weekend Dates for the Bighorn/Horsethief Survey Project:
-April 26th – April 27th
-Memorial Day Weekend: May 23rd – 26th
This is a longer trip due to the holiday weekend
All 3 caves (Bighorn, Horsethief, and Titan) will be open!
-June 21st – June 22nd
-August 9th- August 10th
-September 27th – September 28th

There is a pending project weekend for late October that will be contingent on interest and weather.

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: Ryan Maurer
Data Processing and Storage: Ryan Maurer
Materials: Brian Gindling
Permitting: Jason Forberg
3D LiDAR Scanning: Open Position

Recent Project Trip Reports

Horsethief: Through the crack

June 17, 2023

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

June 17, 2023

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

September 17, 2022

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

September 17, 2022

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

May 22, 2022

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?

March 26, 2022

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)

October 16, 2021

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