- This event has passed.
National Caves and Karst Day
June 6
About National Caves and Karst Day
National Caves and Karst Day is observed on the first Saturday of June each year in the United States, falling on Saturday, 6 June 2026. The day celebrates the remarkable underground landscapes formed by dissolving rock, the ecosystems that depend on them, and the scientific disciplines dedicated to studying them. It is an opportunity for cavers, geologists, conservationists, and curious members of the public to discover the hidden world beneath the surface.
What is National Caves and Karst Day?
National Caves and Karst Day is an annual observance championed by the National Cave and Karst Research Institute (NCKRI), a co-operative entity of the National Park Service based in Carlsbad, New Mexico. The day is dedicated to raising public awareness of cave and karst systems — the underground landscapes formed when water dissolves soluble rocks such as limestone, dolomite, and gypsum over thousands of years. These systems are found on every continent and support a remarkable range of life, from blind cave fish to bacteria that exist nowhere else on Earth.
The day is embraced by caving clubs, national parks, universities, and science museums, many of which open their doors for free tours, public talks, and education programmes. It sits at the intersection of geology, ecology, hydrology, and conservation, making it a genuinely cross-disciplinary celebration.
When is National Caves and Karst Day?
National Caves and Karst Day falls on the first Saturday of June each year. In 2026 it takes place on Saturday, 6 June. Because the date is tied to a day of the week rather than a fixed calendar date, it shifts slightly from year to year. The table below shows upcoming dates so you can plan ahead.
| Year | Date |
|---|---|
| 2026 | Saturday, 6 June |
| 2027 | Saturday, 5 June |
| 2028 | Saturday, 3 June |
| 2029 | Saturday, 2 June |
| 2030 | Saturday, 1 June |
Why Caves and Karst Matter
Karst landscapes cover roughly 15 to 20 per cent of the Earth’s land surface and supply drinking water to approximately 25 per cent of the global population through underground aquifers. In the United States alone, karst aquifers provide drinking water to around 40 per cent of Americans. This makes the protection of cave and karst systems one of the most pressing but least visible environmental issues of our time.
Beyond water supply, caves support extraordinary biodiversity. More than 50,000 species have been described from cave environments worldwide, and scientists estimate that many more remain undiscovered. Cave-adapted species known as troglobites evolve over millions of years in complete darkness, losing eyes and pigmentation while developing heightened senses of touch and smell. Caves also preserve exceptional palaeontological and archaeological records, with cave paintings, ancient remains, and fossil deposits offering irreplaceable windows into human and natural history.
Despite their importance, karst systems are highly vulnerable. Pollutants, over-extraction of groundwater, and surface development above karst terrain can cause rapid and irreversible damage. National Caves and Karst Day plays a role in changing this by helping people understand what is at stake below the surface.
How to Celebrate National Caves and Karst Day
- Visit a show cave — Many cave systems in the United States and beyond offer guided public tours. Visiting a commercial or national park cave is one of the best ways to experience a karst environment safely and learn from expert guides.
- Join a guided caving trip — Contact a local grotto affiliated with the National Speleological Society for an introductory trip into wild caves. Many grottos run beginner outings specifically for newcomers.
- Attend a public event — The NCKRI and affiliated institutions often host talks, workshops, and free cave tours around the first Saturday in June. Check local national parks and cave visitor centres for programming.
- Learn about karst hydrology — Explore how water moves through karst systems and what that means for local water supplies. A surprisingly large number of people live above karst terrain without knowing it.
- Support cave conservation — Donate to or volunteer with organisations such as the National Speleological Society, the Cave Conservancy, or a local grotto working to protect cave environments.
- Teach younger people about caves — Share books, documentaries, or hands-on activities about caves with children to build the next generation of cavers and karst advocates.
- Reduce your impact — If you already visit caves, review Leave No Trace principles for caving: never remove formations, stay on designated paths, and help prevent the spread of white-nose syndrome in bat populations.
History of National Caves and Karst Day
National Caves and Karst Day was established by the National Cave and Karst Research Institute, which was authorised by the US Congress in 1998 and formally established in partnership with the National Park Service and New Mexico Tech. The NCKRI was created to advance cave and karst science, education, and conservation, and National Caves and Karst Day became one of its flagship public outreach efforts.
The choice of June reflects the onset of summer in the northern hemisphere, when national parks and cave visitor centres begin their busiest season and public interest in outdoor exploration is at its peak. The world’s longest known cave system, Mammoth Cave in Kentucky, extends for more than 676 kilometres of surveyed passages and remains a UNESCO World Heritage Site.
Noteworthy Facts About Caves and Karst
- Mammoth Cave in Kentucky is the world’s longest known cave system, with more than 676 kilometres of surveyed passages.
- Carlsbad Caverns in New Mexico hosts one of the world’s largest bat colonies, with up to 400,000 Mexican free-tailed bats emerging each summer evening.
- The Lechuguilla Cave in New Mexico reaches a depth of 489 metres and contains exceptional selenite crystal formations found nowhere else on Earth.
- Karst aquifers supply drinking water to approximately 25 per cent of the global population.
- Cave pearls, formed by dripping water slowly coating a nucleus with calcium carbonate, can take thousands of years to grow to the size of a marble.
- White-nose syndrome, a fungal disease introduced to North America around 2006, has killed millions of cave-dwelling bats.
Frequently Asked Questions
What is National Caves and Karst Day?
National Caves and Karst Day is an annual observance on the first Saturday of June celebrating cave and karst ecosystems, the science that studies them, and the conservation efforts that protect them. It is led by the National Cave and Karst Research Institute in partnership with the National Park Service.
When is National Caves and Karst Day in 2026?
In 2026 it falls on Saturday, 6 June, the first Saturday of the month.
What is a karst landscape?
A karst landscape is terrain formed by the dissolution of soluble rocks, most commonly limestone, dolomite, or gypsum, by slightly acidic water. Characteristic features include sinkholes, disappearing streams, springs, and underground cave systems.
Spread the Word
Help raise awareness by sharing National Caves and Karst Day with your community using #NationalCavesAndKarstDay and #CavesAndKarstDay2026. Whether you plan a cave visit, join a grotto, or simply learn more about the underground world, every bit of attention helps protect these remarkable environments.
Related Awareness Days
- World Water Day — A UN observance highlighting the global freshwater crisis, closely linked to the role karst aquifers play in supplying drinking water worldwide.
- Earth Day — An annual celebration of the planet’s natural environments, including the underground ecosystems that caves and karst represent.
- International Bat Night — Celebrates bats and their habitats, many of which depend on cave systems for roosting and hibernation.
Links
- Visit the National Cave and Karst Research Institute
- Explore more awareness days at AwarenessDays.com
2026 Awareness Days Wall Planner
Every key awareness day at a glance. Perfect for offices, staff rooms, and team planning.
View Calendar →
