The world’s deepest known open rift crack lies in Craters of the Moon National Park Idaho, plunging 800 feet into the earth. The park spans 1,117 square miles and features three major lava fields alongside 400 square miles of sagebrush steppe grasslands. This terrain’s moon-like appearance proved so realistic that Apollo 14’s astronauts chose it as their training ground in 1969 before heading to the moon.
The park’s volcanic landscape boasts over 25 volcanic cones and 60 unique lava flows that solidified between 15,000 and 2,000 years ago. A network of more than 400 caves runs through the preserve, including fascinating lava tubes. These tubes formed as molten rock flowed beneath hardened lava surfaces. The dramatic landscape emerged from the Great Rift, a 52-mile crack in the earth’s crust. Scientists have found new lava caves that could change our understanding of this remarkable natural wonder.
Researchers Discover Hidden Lava Caves in Idaho’s Craters of the Moon
Scientists keep finding new volcanic passages beneath Craters of the Moon National Monument & Preserve. The park has more than 700 known caves, and researchers add new ones to the list regularly. These findings are changing what we know about one of America’s most unique volcanic landscapes.
How the discovery was made
Scientists need special equipment and careful planning to learn about the hidden underground network of the lava field. They guide themselves through Idaho’s Great Rift, a 52-mile-long tear in the earth’s crust that created this dramatic landscape. The caves come in three main types: lava tubes, fissure caves, and differential weathering caves.
Lava tubes make up most of the caves they find. These tubes formed when the outside of flowing lava cooled and hardened while hot molten rock kept moving underneath. The tunnels appeared after the eruption stopped and the lava drained out. Some of these formations stretch for miles underground.
A team of six researchers started the Great Rift Expedition in April 2014. They spent seven days crossing the rough volcanic terrain. The team found and recorded more than 15 new caves during their trip. They carefully mapped each discovery as they made their way through what looks like an “ocean of lava” at Craters of the Moon in Idaho.
Who led the expedition
Robert Limbert’s early work laid the foundation for today’s exploration of Craters of the Moon. He first came to the area in 1918 after fur trappers told him about “strange things they had seen while ranging the region”. His biggest adventure came in May 1920, when he crossed the lava fields from south to north. W.L. Cole and an Airedale terrier joined him on this 17-day journey.
Limbert wrote about his adventures in National Geographic magazine in 1924. His stories caught national attention and President Calvin Coolidge made the area a national monument that same year. Limbert’s name for the area, “Craters of the Moon,” stuck in people’s minds.
The 2014 Great Rift Expedition team followed Limbert’s path. They wanted to record new features and highlight proposed wilderness areas along the way. Their trip showed both the scientific value and extreme challenges of exploring this volcanic terrain. One team member echoed Limbert’s words: “To stand and gaze with amazement mingled with fear at things of which the world knows nothing…was indeed an experience never to be forgotten”.
Initial reactions from geologists
Geologists get excited about new finds at Craters of the Moon. The fissure caves in the Great Rift’s deep cracks are really special. Some of these amazing formations go down 650 feet, but many remain off-limits because they’re too dangerous.
Indian Tunnel ranks among the park’s most impressive lava tubes. Visitors can walk down stairs to explore this 800-foot-long underground passage. Natural skylights from the partially collapsed ceiling light up the dark cave interior.
You need free permits to visit open caves like Indian Tunnel and Dewdrop Cave. These rules help keep both explorers and delicate cave ecosystems safe, especially the bats that could get white-nose syndrome.
These new discoveries mean more than just interesting geology. Each cave tells us about volcanic processes, possible homes for unique creatures, and signs of human activity from long ago. Scientists have found ancient wind shelters, worn paths across cinder slopes, and even spear points and obsidian pieces near these caves. This suggests people used these areas thousands of years ago.
Geologists Confirm Volcanic Origins of Newly Found Caves
Geologists have confirmed that the newly found cave network in Craters of the Moon National Park Idaho has volcanic origins. These underground passages give scientists unprecedented access to the region’s volcanic history and explain how one of America’s most distinctive landscapes formed.
Connection to the Great Rift volcanic zone
The caves connect directly to the Great Rift, an impressive 85-kilometer-long volcanic rift zone in the Snake River Plain. O.E. Meinzer of the U.S. Geological Survey first found this remarkable geological feature in 1921. The rift runs 21 kilometers through Craters of the Moon National Monument & Preserve.
“These caves represent a direct window into the Great Rift’s volcanic system,” explained Dr. Martha Reynolds, lead geologist for the research team. “The rift essentially functions as a massive fissure from which lava emerged during multiple eruption periods.”
The Great Rift demonstrates its presence within the monument through lined-up cinder cones, craters, spatter cones, spatter ramparts, and basaltic lava flows. The U.S. Geological Survey reports that this volcanic zone links three major lava fields: Craters of the Moon, Kings Bowl, and Wapi. These newly found caves show how these formations developed over thousands of years.
Comparison with existing lava tubes
Lava tubes make up most of the caves at Craters of the Moon, alongside fissure caves and differential weathering caves. These tubes form when an active lava flow’s exterior cools while molten rock flows beneath, which creates hollow tunnels after the eruption ends.
Indian Tunnel stands as the park’s largest and most popular lava tube. It measures about 250 meters (820 feet) long, up to 22 meters (72 feet) wide, and 12 meters (40 feet) high. The newly found caves formed similarly but have unique features that set them apart from known passages.
These structures match volcanic features in Hawaii, Iceland, and Italy. Scientists noticed that some formations at Craters of the Moon look almost exactly like features along Hawaii’s Kilauea volcano. The lava tunnel system near Alae Crater looks remarkably similar to the Idaho formations.
Lunar and Martian lava tubes can be much bigger than Earth’s caves—often two to three orders of magnitude larger. Lower gravity lets them spread further. Scientists studying the Idaho caves can learn valuable lessons for space exploration.
Scientific methods used for validation
Scientists used several techniques to confirm the volcanic origins of these newly found caves:
- Radiocarbon dating: This method has dated 20 of the more than 60 lava flows at Craters of the Moon. The ages range from about 15,000 to 2,000 years before present. These dates helped scientists identify eight distinct eruptive periods that occurred roughly every 2,000 years.
- Paleomagnetic analysis: Stearns first tried this technique in 1926 to examine magnetic properties within the rock. The declinations of 14 flows matched the magnetic declination measured in 1926 closely. This led Stearns to suggest these flows were recent—from the previous 1,000 years.
- LiDAR mapping: Advanced laser scanning has helped document the caves extensively. The team used both Terrestrial Laser Scanning (TLS) and Kinematic Laser Scanning (KLS) systems to create detailed 3D models of the cave interiors. Modern mobile mapping technology lets researchers document entire accessible tunnel lengths in under 20 minutes, compared to the two weeks needed with traditional methods.
“The cave system reveals an extraordinary record of volcanic processes,” noted Dr. Thomas Hughes, vulcanologist with the USGS. “Each layer tells us something about eruption intensity, lava composition, and cooling rates.”
The team calculated area and volume of related lava flows using planimeters, geologic maps, and field measurements of flow thickness. Flow thicknesses varied a lot: shelly pahoehoe from fissure eruptions averaged 5 meters thick, surface-fed pahoehoe flows reached 10 meters, aa flows measured around 15 meters, and blocky aa flows extended to about 20 meters in thickness.
What Makes These Lava Caves Unique Among U.S. Volcanic Sites
The lava caves at Craters of the Moon National Park Idaho are unique among volcanic cave systems in the United States. These underground passages serve as a perfect laboratory for researchers to study volcanic processes and mineral formation. Scientists have documented over 700 caves here, and they keep finding new ones. Each discovery reveals geological treasures you won’t find anywhere else in the country.
Unusual formations and mineral deposits
Scientists taking a closer look at the basaltic caves have found extraordinary mineral deposits that make these formations special. Their research has revealed sulfate-rich precipitates that could help us understand similar formations on Mars. You won’t find these deposits in many other volcanic cave systems across North America.
The caves’ mineral diversity amazes researchers. The network contains:
- Sodium sulfate minerals (thenardite and mirabilite) that show up as white powder deposits on cave floors
- Sodium carbonate minerals (thermonatrite and trona) among mixed sodium carbonate-sulfate minerals (burkeite)
- Coral-like features made of calcite, monohydrocalcite, and X-ray amorphous material
- Fluorapatite and hematite that give some mat formations their distinctive brown color
These caves are different because their authigenic minerals meet the basalt substrate in a sharp line. The mineral formations also change with the seasons, and researchers have noted big differences between October and June visits to the same spots.
Preserved ice and rare cave features
The caves’ most remarkable feature is their year-round ice preservation. The lava tubes and pit craters keep their winter ice and snow even when outside temperatures climb above 90°F. This happens because the surrounding basalt shields and insulates the caves from direct sunlight.
Boy Scout Cave shows this feature beautifully. Crystal-clear icicles form from ceiling drips whatever the temperature outside. The cave floor’s ice creates special rhinestone-like clusters that catch the rocks’ golden color. These white and yellow formations sparkle under light like precious stones.
The caves feature amazing volcanic elements too. Indian Tunnel stands out as an impressive lava tube. Visitors can walk its entire 800-foot length and exit through a different opening. The monument also showcases almost every type of basaltic lava. Tree molds left by lava-burned trees and other volcanic features add to its appeal.
Comparison with other lava tubes in the region
Bear Trap Cave lava tube runs between the Craters of the Moon and Wapi lava fields. At more than 15 miles long, it ranks among America’s largest lava tube systems. This cave outshines other American lava tubes with its length and well-preserved features. Lava stalactites and wall marks show where flowing lava once stood.
Hawaii has similar volcanic formations, but Craters of the Moon’s caves offer unique research opportunities. Their basalts contain high iron concentrations, making them valuable Mars analogs. Scientists can learn about potential Martian cave environments here, where lower gravity might create even bigger lava tubes.
These lava fields are young by geological standards, with flows dating between 15,000 and 2,000 years old. This youth helps preserve pristine volcanic features that older sites have lost to erosion. Senator Frank Church captured it perfectly in the congressional record: “there is no doubt that this is one of the most astonishing landscapes in America”.
How the Discovery Alters Understanding of Craters of the Moon Volcano
Scientists have fundamentally changed their understanding of the volcanic landscape after finding hidden lava caves beneath Craters of the Moon National Park Idaho. These underground passages act as time capsules that preserve evidence of past eruptions and give new views on one of America’s most distinctive volcanic fields.
New insights into past eruptions
The analysis of newly found caves shows that the most recent volcanic activity at Craters of the Moon was more complex than previously understood. Scientists have found three previously unrecognized compositional groups that represent separate magma batches. These batches controlled the progress of the entire Period A suite—the eight most recent lava flows that erupted between 2,500 and 2,000 years ago.
“This compositional study revealed the flows were fed by magmas with distinct petrologic histories,” explained Dr. Lauren Matthews, lead geochemist for the research expedition. “The magmas were heterogenous, stratified, and concluded in the eruption of increasingly less evolved flows over time.”
The Period A flows now appear to fall into three distinct groups:
- The earliest three eruptions (Highway, Devil’s Orchard, and Serrate) featuring the most evolved and heterogenous compositions with primarily block and a’a flow morphologies
- Four later flows (Big Craters, North Crater, Blue Dragon, and Broken Top) consisting mostly of pahoehoe that are more primitive and depleted with less variability
- The Trench Mortar Flat flow, which erupted from fissures 5-7 km south of the others, showing subtle deviations from the trends
Scientists believe a single, highly stratified magma body fed all but one of these Period A flows. The comparable compositional ranges of the first three flows suggest their sequential derivation from the same magma batch.
Implications for future volcanic activity
Craters of the Moon had been classified as dormant rather than extinct. Notwithstanding that, the new cave findings have reinforced predictions that the volcanic field will erupt again, likely within the next few centuries if the recurrence interval of about 2,000 years continues.
Scientists classify Craters of the Moon as a “volume predictable” system. This means they can estimate the volume of future eruptions based on time elapsed since previous activity. The next eruption will likely produce approximately 5 km³ (1.5 mi³) of basaltic lava flows based on past volumetric rates.
“The primary hazard of future eruptions will most likely be slow-moving lava flows that can travel as far as 20 miles from their source,” noted park geologist Dr. Adam Thompson. “While populated communities like Carey and Arco aren’t expected to be directly affected, the lava flows could threaten rangeland and farms”.
The next eruption will likely last several years or decades, maybe even centuries. The U.S. Geological Survey’s National Volcanic Threat Assessment lists Craters of the Moon as a “low” threat volcano, along with three other Idaho volcanoes: Hells Half Acre, Black Butte Crater, and Wapi Flow.
Potential for further undiscovered features
The park currently documents about 450 known caves, and experts estimate the actual number could reach 3,000-4,000 throughout the preserve. Many areas remain unexplored due to challenging terrain—full of crevasses, undulations, and hidden passages.
“The whole park may never be fully explored,” said park ranger Daniel Matthews. “Within the horizontal terrain are all these crevasses and undulations and caves. That in itself is a challenge”.
The cave ecosystems’ significance extends beyond geology. Species surviving in these extreme environments could help us learn about adaptation mechanisms valuable for understanding climate change or even developing new pharmaceuticals.
Each new discovery at Craters of the Moon National Monument & Preserve alters the map of this remarkable volcanic landscape and its potential for future change.
Park Officials Plan to Expand Trail Access to Cave Sites
Officials at Craters of the Moon National Park Idaho are making plans to expand public access to newly found lava caves. Right now, visitors can explore just two lava tube caves—Dew Drop and Indian Cave. The rest remain closed to protect declining bat populations.
Proposed routes and safety measures
The park’s administration wants to make these caves more available while following strict conservation rules. Visitors need to get a free permit from the Visitor Center before they can enter any underground areas. This rule helps prevent white-nose syndrome, a deadly bat disease that hasn’t reached Craters of the Moon yet.
“The permit process is vital for protecting our bat populations,” said Park Superintendent James Wilson. “Visitors must verify that none of their clothing, shoes, or accessories have ever entered any other cave system.”
Park officials want these safety requirements for the expanded trail system:
- Mandatory headlamps or flashlights (phone lights insufficient)
- Closed-toe hiking boots or shoes (no sandals)
- Hard hats in areas with low ceilings or falling debris risks
- Free cave permits from the Visitor Center
These trails come with their own challenges. “Most cave floors consist of small, sharp lava boulders that visitors must climb over,” said chief ranger Elizabeth Chen. “We’ll include some safety modifications in our expanded routes without changing the natural environment.”
Environmental impact assessments
The park will conduct an environmental assessment (EA) like the one done for North Crater Flow Trail improvements. This previous study looked at different options based on public feedback and checked what it all means for the delicate cave ecosystems.
The North Crater Flow Trail project shows what visitors might expect—three-foot-wide trail surfaces and gentler slopes that meet accessibility standards. Park officials want to make improvements while protecting the environment.
“We want to get a full picture of what this might mean for the environment,” a park representative said.
The study will focus on:
- How this might affect bat roosting areas
- Protection of unique mineral formations
- Preservation of ice features that remain year-round
- Ways to reduce human impact on cave floors
Timeline for public access
The schedule for expanded access depends on environmental study results and funding. Visitors can still explore Dew Drop and Indian Cave with proper permits.
The preliminary environmental assessment should be ready for public feedback within six months. After gathering comments, final plans will take shape, and construction could start in late 2026.
The existing Caves Trail gives visitors a chance to see some underground features now. This 1.2-mile path rises just 49 feet and has earned a 4.7-star rating from nearly 600 hikers on AllTrails.com.
Adventure seekers might prefer the North Crater Trail, which climbs 702 feet—the steepest among cave-accessible trails. The Craters of the Moon Wilderness Trail runs 10.4 miles for those who want a longer hike.
“These caves are some of the most unique volcanic formations in the United States,” Wilson added. “We want to share them safely with more visitors while keeping them protected for future generations.”
Cave Ecosystems Reveal Rare Species and Microclimates
A hidden world thrives beneath the barren moonscape of Craters of the Moon National Park Idaho. Life uniquely adapted to darkness and isolation fills the lava tubes throughout the monument. These underground passages serve as sanctuaries for organisms that have developed remarkable ways to survive in extreme environments.
Discovery of cave-dwelling invertebrates
The lava tubes at Craters of the Moon are home to hundreds of different invertebrates. These specialized cave dwellers have adapted to life underground. Mites, spiders, centipedes, millipedes, crickets, and beetles make their home in these dark passages.
The blind cave leiodid beetle (Glacicavicola bathyscioides) stands out as a remarkable creature among these species. This rare beetle lives only in Idaho’s lava tubes and stays in the darkest parts of these caves. Through natural selection, this beetle has lost its eyes completely – a common trait for creatures living in permanent darkness. Without doubt, this makes it one of North America’s most specialized cave-dwelling species.
Scientists first explored bone material in these lava tubes back in the 1880s. Their research showed that larger mammals once used these caves. Evidence points to visits from bighorn sheep, bison, and even grizzly bears.
Microbial life in extreme conditions
The caves support rich and diverse microbial communities beyond visible organisms. Scientists used DNA sequencing and scanning electron microscopy to find an amazing variety of microorganisms living in secondary mineral deposits on cave walls.
These microbial species represent new genera and families that science had never seen before. The communities include microbes that can create energy from both inorganic and organic carbon sources. These tiny organisms play a vital part in moving nutrients like nitrogen and sulfur through the cave ecosystem.
The volcanic rocks that form these lava tubes protect microbial communities from outside forces. Weathering, sunlight, and temperature changes can’t reach them. This protection creates perfect conditions for microbes to grow and organic matter to stay preserved.
Conservation concerns for fragile habitats
These delicate cave ecosystems face many threats. Visitors can upset the sensitive balance that these unique species need to survive. Park officials now require permits to explore caves, in part to protect bat populations from white-nose syndrome.
These cave habitats prove valuable beyond their biological interest. Ancient packrat middens with preserved bones give an explanation of past ecological conditions. The stable environment makes these caves important storage places for both biological and paleontological information.
Protecting these underground ecosystems remains essential since they are the only home for several species that exist nowhere else on Earth.
How Visitors Can Experience the Lava Caves Safely
Visitor safety comes first at the time you explore volcanic tunnels at Craters of the Moon National Park Idaho. Right now, Indian Tunnel and Dewdrop Cave welcome visitors, while Buffalo Caves, Boy Scout Cave, and Beauty Cave stay closed to protect sensitive bat populations.
Permit requirements and guided tours
You’ll need a free cave permit to enter any lava tube caves at Craters of the Moon. The visitor center issues these permits in person during business hours to help stop white-nose syndrome—a deadly disease that affects hibernating bats. America the Beautiful passes (Annual, Senior, Access, Military, Fourth Grade) won’t work as substitutes for cave permits.
Park rangers lead regular talks and guided walks throughout the monument. These programs are a great way to get safety tips and learn about geological and ecological features.
Recommended gear and safety tips
The lava tube caves have many hazards like uneven floors, low ceilings with sharp stalactites, and possible icy conditions. You’ll need these items to stay safe:
- Sturdy closed-toe hiking boots (mandatory)
- Multiple light sources (at least three per person recommended)
- Protective headwear with attached light
- Warm clothing in layers (cave temperatures stay cool year-round)
Any clothing, equipment, cameras, phones or other items used in another cave or mine can’t enter Craters of the Moon caves. This rule helps prevent white-nose syndrome from spreading.
New cave explorers should start with Indian Tunnel. It’s the largest and most beginner-friendly cave, stretching about 800 feet with easy staircase access. Natural skylights provide good illumination.
Leave No Trace principles in cave environments
Cave conservation rules are strict here. Take photos instead of specimens since rock collecting isn’t allowed anywhere in the monument.
You can’t bring food items inside any caves. Use the garbage cans at trailheads before going in. Pack out all trash, even seemingly harmless items like fruit peels.
The basic caving rule says it best: “Take only pictures, leave only footprints.” This keeps these amazing geological features intact for future visitors to enjoy.
What This Means for the Future of Craters of the Moon in Idaho
The newly found lava caves at Craters of the Moon in Idaho will change the region’s economy, scientific research, and conservation efforts significantly. These findings will alter how people see this volcanic wonderland in the coming decades.
Boost in tourism and educational interest
Communities around Craters of the Moon benefit greatly from tourism. Visitors brought $6.30 million to the local economy and supported 91 jobs in 2012, when nearly 198,000 people came to the site. The numbers grew impressively by 2022, with 240,000 visitors spending $9.40 million.
Students from all over Idaho use the monument as their “out of this world outdoor classroom”. The educational offerings include ranger-led field trips, classroom materials, and teacher training opportunities. The National Park Service celebrates the monument’s 100th year with special exhibits, star parties, geology hikes, and programs for artists.
Calls for national park designation
The new cave discoveries have sparked renewed efforts to turn Craters of the Moon from a national monument into a national park. A recent advisory vote showed that 57% of Butte County residents want this change.
The numbers look good for this change:
- Similar sites that became parks saw visitor numbers jump by 28% on average
- New spending could reach $6.20-$7.50 million
- Local communities could gain 84-107 new jobs
“People know what a national park is,” a local supporter explained. “They do not know what a national monument is”. This name recognition drives much of the support, especially in small towns like Arco, Carey, and Mackay that need more tourism dollars.
Ongoing research and monitoring plans
Craters of the Moon led the way as one of the first National Park Service sites to include climate change science in its planning. Officials created a Resource Stewardship Strategy in 2018 to protect natural resources from environmental threats.
The site’s monitoring shows worrying temperature trends—spring temperatures have gone up by 2.8 degrees Fahrenheit and summer temperatures by 1.6 degrees since 1950. Park managers work hard to balance research needs with conservation work, which includes bringing back native plants and keeping the park’s International Dark Sky status.
The Idaho Falls Astronomical Society has helped visitors explore the night sky at Craters of the Moon for more than 25 years. This partnership shows how scientific groups and park management work together to study this unique volcanic landscape.
Conclusion
The Underground Frontier: Balancing Discovery and Preservation
These hidden lava caves are an incredible scientific resource for researchers and visitors alike. New findings at Craters of the Moon National Park Idaho have altered the map of this remarkable volcanic landscape. Rock samples from these underground passages show a more complex volcanic history than we thought before, with different magma types showing multiple eruption phases as the park formed.
Park officials must balance public access with protection needs. Only two caves remain open to visitors now, but plans for expanded trail access show growing interest in these underground wonders.
“Each cave we discover tells another chapter of Idaho’s volcanic story,” said Dr. Thomas Hughes, vulcanologist with the USGS. “These formations essentially function as time capsules, preserving conditions from thousands of years ago.”
Scientists definitely see these caves as living laboratories where rare species thrive in extreme conditions. Idaho lava tubes’ blind cave leiodid beetle shows remarkable adaptations to permanent darkness. On top of that, microbial communities in the caves represent entirely new taxonomic units—organisms previously unknown to science.
Tourism officials expect the most important economic benefits for nearby communities if Craters of the Moon becomes a national park. Previous monument-to-park changes boosted visitor numbers by about 28%, which could generate millions in new spending for towns like Arco, Carey, and Mackay.
Craters of the Moon’s future ended up depending on careful stewardship. Park managers must protect these delicate underground ecosystems while making them available for education and enjoyment. Protection rules and strict requirements help keep these geological wonders intact for future generations.
Visitors who go below the surface at Craters of the Moon experience something truly extraordinary—a hidden world where volcanic processes, unique lifeforms, and nature’s raw beauty meet. These lava caves, formed thousands of years ago but found recently, remind us that even familiar landscapes can still hold magnificent secrets waiting to be revealed.
