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This is the trailer link for the giant screen film ANCIENT CAVES.

This is an incredible science adventure film, and a story of exploration. The film begins in John Ackerman’s Spring Valley Caverns, and focuses on the amazing scientific findings which are being discovered there. The underwater sequences are being shot in the most beautiful and dangerous caves in the world.

The trailer is in 4:3 aspect ratio as this is an OMNIMAX format dome original, and will obviously look a little distorted and strangely composed on a small flat screen. ANCIENT CAVES is the first giant screen film to be produced exclusively for the OMNIMAX theaters in over 30 years. This astounding film will be shown at the St. Paul Science Museum’s Omnitheater in Fall 2018. 

Puzzle Solved!

We had originally thought that the occasional dead raccoon or skunk we would find at the base of the Moon & Stars Pit had been thrust up from the underground river, which would sometimes rise up into the cave after mega rain events. Now we have the real facts.

A small hole had opened up on the surface, where inquisitive mammals would find a quick route into the cave. Recently, after a heavy rain, this hole became larger, allowing us to see daylight 140 feet up from the cave floor!  It will be necessary to span the hole near the surface with I-beams and concrete to seal it.

Breaking News in Tyson Spring Cave!

January 25, 2014


Emily Hudson after a grueling 14-hour trip.

Learning from others who have made fatal mistakes is always a wise choice.  Venturing deep into Tyson Spring Cave during a rain or snow melt event could morph into a really bad day, so the last frozen Saturdays in January were perfect for forging ahead with unfinished business.

In 2008, two years after I created a safe man-made entrance into the cave, an ancient moose antler and saber tooth cat skull were discovered in Tyson’s.  This sent shock waves through the scientific community and made international news . . .

Click here to read the full article.

Fountain Spring Cave Story, The Quest for the Unknown

Part 1

I have always been fascinated by old local mysteries. When I first heard the story of Fountain Spring Cave in 2012, I was immediately captivated when I learned about the years of the relentless, endearingly optimistic search by some of the area’s most notable young men. Their daring displays of courage and ceaseless fortitude, and what became of them and the cave they fought so hard to find, captured my imagination and snared me, body and soul.  I could imagine what it was like to be Earl Kidd, and could identify with his quest for a personal Holy Grail, a long lost treasure waiting to be uncovered.  And eventually, the idea crept on me that maybe I could finish what he had started, that I could find what may have never been found…

Click here to read the full article.

Diving the Cistern Pit in Holy Grail Cave

Kirk Moorhead dove the Cistern Pit in Holy Grail Cave. He traveled approximately 400 feet along a low, 4-foot-wide, fully submerged passage. He eventually surfaced into a dry passage, which he will explore in the near future. This dry passage may be the gateway to the largest cave network in the upper Midwest.

Fountain Spring Cave Update

We are about one week away from breaking through!

Sump Dive in Tyson Spring Cave

Kirk Moorhead dove the terminal upstream sump in Tyson Spring Cave. He traveled over 250 feet before the walls squeezed inward to form a vertical fissure. Looking up, he could see a mirrored surface, indicating airspace; however, he was unable to squeeze up the fissure.

2014 Summer
Quartz Road Cave

It took less than 30 minutes to open this cave on the newest farm that John purchased, which is located along the far eastern boundary of the Cave Farm. The main room in the cave actually lies under Quartz Road!  A permanent entrance has now been installed.

2014.6.21 & 6.28
Hilltop Spring Cave

Mark Phillips and his daughter Stephanie discovered a strange hole in a field on the Cave Farm. A culvert entrance was installed, and the one room cave was explored and probed.  After exhausting all efforts to locate a cave from the bottom of the room, the Cave Finder was pressed into action.  After excavating 30 feet, a 35′ long stream passage was discovered. Because the passage narrowed down, and there were no signs of the cave opening up, we surveyed the cave, photographed it and resealed the sink hole.

New Bridge

The old rotted wood bridge in Spring Valley Caverns has now been replaced with a stainless steel unit.  Wow, what an improvement!

MN Cave Preserve on The Osgood Files.  Charles Osgood on the CBS Radio Network

Click here to download the audio file.

MN Cave Preserve on CBS This Morning

Click the links above to be taken to the CBS site or click here to download the video excerpt.

Diving a Sump in Holy Grail Cave

Tim Forde, Janine Cross, Penny & Stephan Shimizu, Brett Lucas, Emily Hudson, John Ackerman
Terry Trinka Ddve Cistern Pit Sump and traveled 150′ due east. Keeps going wide open.

Trip to Inner Space Caverns near Austin, TX

In Austin, TX, we got a great cave tour in Inner Space Caverns by our tour guide, Ken.
Then Billy and Tony showed us the Hidden Passages tour – both the part open to the public now and the part about to be opened up.

The thing that amazed us the most was the variability – different types of ceiling, formations, pools of water, different levels, and lily pads.

There are formations as crystal clear as ones found in the Caves of Sonora. While there aren’t many helectites, there is some seriously amazingly clear bacon.

And the cave – even in a drought – is wet enough to still be growing. More pictures to come; here are the first ones.

Great Trip for Beginners The First Two Saturdays of December

This coming Saturday, Dec. 7th, and next Saturday, Dec. 14, we are working on a dig site deep into Holy Grail Cave.
But it is through some of the easiest passages to navigate and is an ideal trip for beginners or someone wanting to try caving.
For more information, please send an email to

The Associated Press just released an article about the Cave Preserve!

Click here to read the article on the AP website or click here. Please note that you will need to click the image again to zoom in as your browser’s default will be to zoom out so you can see the entire image.

Here is a short video on AP’s YouTube channel.

Here are a few other places this article appeared:
Yahoo News
Rochester Post Bulletin
Minneapolis/St.Paul Star Tribune
Seattle Times
Fox News Philadelphia

The Bat River Cave Map is finally finished!

Hollow Earth News – Wisconsin Speleological Society’s September Newsletter

Our incredibly active caving club neighbors of Wisconsin released a great article about the Fountain Spring Cave Project for their September issue.

Feature Story in the NYTimes

Click here to read the article on the NYTimes website or click the picture below to read about the MN Cave Preserve.
For a larger-scaled picture, please click here, but please give the page more time to load.

Fountain Spring Cave Project Update

Help excavate this sinkhole and find the large cave that lies below it!

New Cave Discovery

Mark Phillips and daughter Stephanie periodically inspect the 600-acre Cave Farm for newly opened sink holes.  Yesterday they were successful!

John Ackerman dropped down the hole and discovered a 10′-12′ diameter room, about 4′ high.  Since this sinkhole was formed on top of a hill, it is no doubt the dome of a cave below.  An unknown quantity of rocks and mud will need to be hauled out before anything further can be found.  Since there are other projects going on right now, this one will have to wait its turn.  The sinkhole will be stabilized until then.

Goliath’s Cave – Final Report 2013
Goliath’s Cave Map

The DNR continues to degrade our cave.

Spring Valley Caverns in Jan. 2013 Issue of Smithsonian Magazine!

Click here to view the article on Smithsonian’s website.

Be sure to check out the additional photos in the gallery – clickable on the first page of the story.

The full story can be downloaded here.

New changing shack at Holy Grail Cave.

Lights and lower skirt for the building will be installed soon.
I know it looks cockeyed, but it is actually level.

Quarry Hill Nature Center visits SVC for a late night tour.

The Geology Department from Carleton College visits Spring Valley Caverns.

Cave Farm Expansion


Since 1989, I have been hard at work making the dream of a protected cave preserve for future generations to learn from and enjoy come true. I have, now more than ever, the drive, ability, and experience to expand this project.

Recently, I purchased a farm on the eastern border of the Cave Farm. This increases the Cave Farm to almost 600 acres and provides direct access from another county road. And it came with a bonus — a nice, deep sinkhole!

In short order, I discovered a cave below that sinkhole. I am continuing to widen a passage that looks quite promising, which will hopefully lead to a network of as-of-yet unexplored cave passages. This is the 36th cave to be discovered on the Cave Farm.

I also recently purchased another parcel in Fillmore County, which I can not yet disclose at this time; however, I can tell you that a significant cave will be opened up under that property.

Please see the Cave Farm map for the new boundaries of the Cave Farm, provided by Al Lewerer.

-John Ackerman

International Report on Ancient Bones Found in Tyson Spring Cave Finally Released!!

Boreas publication; Chris Widga et al Homotherium Minnesota Abstract:

A scimitar-toothed cat (Homotherium serum) and stag moose (Cervalces sp.) are described from Tyson Spring Cave, Fillmore County, Minnesota. These specimens represent the first records of both species in the state, and the first record for H. serum in the Great Lakes region. Although the Cervalces specimen remains undated, it shares features with pre-Wisconsin specimens from the eastern Great Plains. The H. serum individual dates to c. 26.9 ka, when the Wisconsin ice margin was less than 60 km away. Genetic analyses support the identity of the Homotherium specimen as conspecific with Homotherium serum found in older Beringian deposits, as well as both the early divergence of tribes Homotherini and Smilodontini within Machairodontinae and the early divergence of this Machairodontinae from the lineage that produced extant cats.

Scout Group Trip Into SVC I and IV

On Friday October 19th, a caravan of vehicles from the Twin Cities, consisting of approximately 20 adults and adolescents, arrived at the Cave Farm for a weekend of fun. At 9 a.m. the following morning sixteen eager souls were suited and waiting patiently at the entrance to Spring Valley Caverns. The group was voluntarily split in half. Some chose the “Oh my God, I hope I survive this” tour with Kimber Anderson, and the other half chose the alternative with John Ackerman. By late in the day everyone in John’s group had experienced the wonders of SVCIV and SVCI, and everyone in Kimber’s group was elated and exhausted. My group appeared composed and relaxed, while Kimber’s group looked and felt as though they had challenged the cave and had conquered the beast. They all spent Saturday evening around the campfire, enjoying the beautiful weather and appreciative of the experience.

Look what we found!


In about 10 minutes of digging in the sinkhole, we found a crack. After sliding on your stomach for 5 to 6 feet, you slide right down into a *huge* room. This one’s going to be a big one, maybe even the next Holy Grail.

Sinkhole Excavation

This Saturday!! I recently discovered a sinkhole on the King farm and will excavate it this Saturday.
The sinkhole is rather small and won’t take long to probe. Afterwards, it’s on to caving!
If interested, please post on the blog – it’s now set up to send me email notifications!!
To manage your own email notifications, simply log in and go to your Settings by hovering over the “Minnesota Caving Club” link in the top left corner and choosing Dashboard.

Let me know if you have any questions or run into any problems,


Experienced Caver Needed

We have room for one cave explorer not afraid of tight spaces OR heights. Will be crossing a huge chasm into an entirely new section of Holy Grail. Saturday, June 9th is the target date.
Need to leave the cities early AM, be in the cave by 9AM, and it will be ALL DAY trip, so need to have some serious stamina. If interested, contact John asap at Thanks!

Pictures from SVC I to SVC III 2012.4.15

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