Alaska’s Frozen Underground Permafrost Tunnel That Is Hiding In Plain Sight

CRREL Permafrost Tunnel - Fairbanks, Alaska

 By: Courtney Dowd-Stanley 

Alaska’s frozen underground permafrost tunnel is quite the sight to see. The tunnel runs through permafrost, a natural frozen phenomenon hiding under the surface of the ground, and brings it into plain sight. Alaska's underground permafrost tunnel Flickr - Travis
So, what is permafrost? Permafrost is permanently frozen ground made up of soil, rocks, or sediment. Technically, in order to be classified as permafrost, ground must be at a temperature of 32 degrees F (0 degrees C) or less for more than two years. Structurally, permafrost is incredibly important as its melting can cause erosion, landslides, and a variety of ground subsidence issues. It may come as a surprise to some, but permafrost can be found beneath nearly 85 percent of Alaska’s ground surface. It is, however, thickest in the arctic regions of the Last Frontier, north of the Brooks Range. Alaska's underground permafrost tunnel Flickr - Public Affairs Office Fort Wainwright
With permafrost being such a prevalent part of Alaska’s landscape, it makes sense that there would be a facility that allows researchers to study it up close. The United States Army maintains and operates the Cold Regions Research and Engineering Laboratory (CRREL) Permafrost Tunnel Research Facility located 16 miles north of Fairbanks in Fox, Alaska. CRREL is a part of the U.S. Army Corps of Engineers Engineer Research and Development Center. As the tunnel serves as an active underground laboratory it is not open to the public, but a virtual tour is available through the CRREL website HERE. We’ve also included a YouTube video touring the facility below. Alaska's underground permafrost tunnel Flickr - Public Affairs Office Fort Wainwright
The tunnel is carved into the side of a molehill and is reported to be roughly 50 feet underground and 360 feet in length. It was built between 1963-1969 in order to study underground excavation methods in permafrost, but it was soon realized that the tunnel would be a great place to study natural sciences such as geology and paleontology along with a variety of mining and construction methods in frozen environments. Alaska's underground permafrost tunnel Flickr - Travis
The frozen environment inside the tunnel is over 40,000 years old and is filled with fascinating soil, rock, and paleontology features. As you navigate through the tunnel via the virtual reality tour, you’ll notice ice-crusted roots hanging from the ceiling. Alaska's underground permafrost tunnel Flickr - Travis
Many of the ice wedges formed inside the tunnel turn distinctive shades of amber colors when trapped air bubbles combined with sediment mix together in such small, confined spaces. Alaska's underground permafrost tunnel Flickr - Public Affairs Office Fort Wainwright
While the specific area was once thought to be the underside of an ancient lake, more recent studies have shown that it might actually just be another filling of cracks with water turned to ice. Alaska's underground permafrost tunnel Flickr - Travis
Inside, a truss system keeps the tunnel safe and secure from collapsing. A refrigeration system with flexible ductwork placed throughout the tunnel is used to assure that the ground stays frozen during Fairbanks’ notoriously hot summer months. The system also helps blow cold outside air through the tunnel in the winter. There are also extensive walkways to keep visitors from walking on the slippery silt underneath the metal paths. Alaska's underground permafrost tunnel Flickr - Public Affairs Office Fort Wainwright
Whether you are a lucky researcher who gets the opportunity to study this unique permafrost tunnel up close and personal, or you are just an interested bystander (like us) taking the online virtual tour, this unique attraction is a must-see. You’ll have the chance to learn about ice wedges, ice lenses, and other permafrost features including the discovery of bones from the Pleistocene of bison, mammoth, and horse. Alaska's underground permafrost tunnel Flickr - U.S. Army Corps of Engineers
Check out the incredibly interesting YouTube video below to experience a glimpse inside this unique permafrost tunnel in Fairbanks.
Looking for more where that came from? You'll love learning about El Capitan Cave, Alaska's largest aboveground cave that will give you an enchanting middle-earth type of experience. Check out Matanuska Glacier: Visiting One Of Alaska's Most Amazing And Easily Accessible Places. You might also enjoy reading about the isolated places in Alaska where you can actually view Russia from your doorstep. This historic read on Portage - The Sunken Alaska Ghost Town That Nature Is Reclaiming is also quite interesting.
If you are living and loving The Alaska Life – share your adventures with us on our Facebook page HERE, and they might just end up getting featured in one of our next blog posts.
Written by Courtney Dowd-Stanley 


Our ecology class visited the tunnel when I was a biology student at UAF (Univ. of Alaska Fairbanks) in 1998-99 (?).
It was absolutely fascinating and the one thing that I remember most was the smell!
When warming occurs (like near the tunnel entrance), the organic matter in the frozen soil thaws and starts to decompose. It was an overwhelming rotten, musty smell.
Smelly but cool!! I’m grateful I got the opportunity to visit the facility.

Jennifer Butler April 17, 2021

I was listening to the NPR Hidden Brain episode (20200121) and looked up the tunnel, but your website link “CRREL website HERE” link does not work…sounds like a fascinating place…the YouTube video was interesting….hope you get the link fixed.

Yumi Muraoka April 17, 2021

Hi Yumi! We got that fixed for you :)

Kyle April 17, 2021

I was spending the summer of 2012 with my daughter in North Pole. She learned that the tunnel was being opened one day only for public tours. We went to the tunnel and were lucky enough to be included in the limited groups. It was quite an experience, and very interesting. As a visiting Texan, I felt especially lucky to get the opportunity that so few people ever have.

Toni Rash April 17, 2021

I thought it was bad to tunnel underneath the permafrost ????

Johnny Arana April 17, 2021

My mom was part of the original crew that worked at the permafrost testing institute with jack! Good memories for sure!

Shawn Larson April 17, 2021

Coming to Fairbanks again this August. Interested in a tour

Carla Snyder April 17, 2021

I was born and raised here and would like to go on this journey!!7

B woods April 17, 2021

We will be in Fairbanks in August 2018 with teenage granddaughters and would love to take a tour. Are there tours available to the public?

RITA GRIGGS April 17, 2021

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