10 Most famous caves in the world - Marvels beneath the Earth’s surface

1. Son Doong Cave, Vietnam: World’s biggest cave

Son Doong Cave is located in Phong Nha-Ke Bang National Park in Quang Binh, Vietnam. This UNESCO World Heritage site is renowned for its extensive limestone karst landscape and dense jungle, contributing to the cave’s remote and pristine environment.

How big is Son Doong Cave?

Son Doong Cave holds the title of the world’s largest cave by volume (38.5M cubic meters). The main cavern is over 9 kilometers long, 200 meters high, and 150 meters wide. This size allows entire city blocks with skyscrapers to fit inside. Some sections of the cave feature underground jungles and rivers, further emphasizing its colossal dimensions.

Son Doong Cave was formed around 3 million years ago through the erosion of limestone by river water. The cave features massive stalagmites and stalactites, some of the largest in the world, reaching heights of up to 70 meters. Also, the cave is known for its “Great Wall of Vietnam,” a 90-meter-tall calcite barrier (25m vertical and 65m with a slope of 45 degrees), and two enormous skylights (namely Doline 1 and Doline 2) that allow sunlight to penetrate, fostering a lush forest called the Garden of Edam on the inside.

Due to its challenging access and the desire to preserve its pristine condition, Son Doong Cave Expedition Tours is not for everyone. Every year, only 1,000 visitors are granted permits to explore this natural marvel, all exclusive through Oxalis. Target tourists are typically experienced cavers and adventure seekers willing to undertake a rigorous journey, including a multi-day trek and river crossings. This, combined with the cave’s unparalleled beauty, makes Son Doong a bucket-list destination for nature enthusiasts worldwide.

Son Doong Cave is the world’s largest cave by volume at 38.5 million cubic meters.

2. Mammoth Cave, USA: World’s longest cave

Mammoth Cave (so named due to the “mammoth” size of the chambers) is a part of the Mammoth Cave National Park in central Kentucky, USA. This park is part of the Green River Valley and is easily accessible from major cities like Louisville and Nashville.

Is Mammoth Cave fully explored?

As the world’s longest cave system, Mammoth Cave has over 675 kilometers (420 miles) of surveyed passageways, and ongoing explorations could potentially extend its known length. The cave’s intricate network of tunnels and chambers is a favorite among speleologists.

Mammoth Cave’s formation dates back several million years, resulting from the erosion of Mississippian limestone by acidic groundwater. This process has created vast chambers, narrow passageways, and extensive underground rivers. Notable features include the “Frozen Niagara” with its stunning flowstone formations, the vast “Grand Avenue,” and the “Bottomless Pit.” The cave also houses unique gypsum formations and rare mineral deposits, adding to its geological significance.

Mammoth Cave National Park attracts over half a million visitors each year, making it a major tourist destination. The cave offers various tours catering to different interests and physical abilities, ranging from short walks to strenuous spelunking adventures. Families, history buffs, and nature lovers are particularly drawn to Mammoth Cave, thanks to its rich history, biodiversity, and the chance to experience the world’s longest cave.

Mammoth Cave is the world’s longest cave system with over 675 kilometers (420 miles) of surveyed passageways.

3. Veryovkina Cave, Georgia: World’s deepest cave

Veryovkina Cave is located in the Arabika Massif, a glacially eroded karst, on the Gagra Mountain Range in the Western Caucasus region of Georgia. This remote area is part of the Greater Caucasus Mountains, offering a stunning backdrop for caving expeditions.

Veryovkina Cave (also spelled Verëvkina Cave), named after the speleologist Aleksander Verevkin, is the deepest cave in the world, plunging to a depth of 2,212 meters (7,257 feet) and a length of 17.5 kilometers. Its vertical extent challenges even the most seasoned cavers, with its depth representing the pinnacle of underground exploration.

The cave’s formation is a result of complex karst processes, where weak acidic water gradually percolates through limestone, dissolving it and creating deep, narrow shafts and vast chambers. Veryovkina Cave is characterized by its extreme verticality, with numerous pits and drops requiring technical climbing skills. The cave’s features include massive underground water pools, intricate passageways, and vast chambers.

Due to its extreme depth, Veryovkina Cave is not a typical tourist destination. It only attracts a niche group of elite cavers and speleologists with advanced technical skills and gear.

Has anyone reached the bottom of the Veryovkina Cave?

Although it has taken over five decades and many expeditions for cavers to reach the record depth, they believe more is still to be found. As the world’s deepest cave, Veryovkina Cave draws those who seek the ultimate caving challenge and the opportunity to contribute to ongoing explorations in one of the most extreme environments on the planet.

4. Eisriesenwelt, Austria: World’s biggest ice cave

Eisriesenwelt, German for “World of the Ice Giants,” is located in the Hochkogel mountain in the Tennengebirge section of the Austrian Alps, near the town of Werfen. This majestic ice cave is only 40 kilometers south of Salzburg, making it easily accessible for tourists.

What is special about the World of the Ice Giants?

Eisriesenwelt is the largest ice cave in the world, stretching over 42 kilometers. However, the ice formations, which reach a thickness of 20 meters (65 feet), are concentrated in the first kilometer of the cave, where the spectacular ice structures can be found, and the only area tourists are allowed to visit. Limestone makes up the remaining part of the cave.

Eisriesenwelt is primarily a limestone cave with impressive ice formations that result from the unique combination of temperature, airflow, and water seepage. During spring and summer, melting snow and rainwater seep into the cave, freezing upon contact with the cold air inside. This process creates magnificent ice stalactites, stalagmites, and frozen waterfalls. One of the most notable features is the “Eispalast” or “Ice Palace,” a grand hall filled with intricate ice sculptures that glisten in the cave’s eerie light.

Eisriesenwelt, a very famous cave, attracts around 200,000 visitors each year, drawn by the stunning natural ice sculptures and the thrilling adventure of exploring an underground ice world. Guided tours to Eisriesenwelt are offered from May to October, providing visitors with insights into the cave’s formation and history while ensuring their safety. The cave’s natural beauty and proximity to Salzburg make it a must-visit attraction in Austria.

Eisriesenwelt is the largest ice cave in the world, stretching over 42 kilometers.

5. Cueva de los Cristales, México: World’s biggest crystal caves

Cueva de los Cristales, or the Cave of Crystals, is located in Naica, Chihuahua, Mexico. It was discovered in 2000 and lies nearly 300 meters below the surface, beneath the Naica Mine, an active mine with a substantial lead, zinc, and silver deposit.

What is special about the Cave of Crystals?

Cueva de los Cristales is relatively small (27 meters long) compared to other caves on the list, but its chambers contain some of the largest natural crystals ever discovered. The largest cave crystal ever found in Cueva de los Cristales measures 12 meters in length, 4 meters in diameter, and weighs up to 55 tons.

Cueva de los Cristales is a famous cave for its gigantic selenite crystals, which formed over hundreds of thousands of years. The cave’s unique conditions—high temperatures (up to 58°C) and relative humidity (between 90 and 99%)—allowed these crystals to grow to their enormous sizes. The environment inside the cave is extreme, with temperatures that can cause heat stroke in minutes, making exploration a considerable challenge.

Due to its inhospitable environment and the fragility of the crystals, Cueva de los Cristales is not open to the general public. Access is restricted to scientists and researchers studying the crystals and the cave’s unique geology. However, the cave has gained international fame through documentaries and publications, attracting significant interest from the scientific community and adventure enthusiasts. Special tours are sometimes arranged for professionals, but these are rare and strictly controlled to preserve the site.

816 Nuclear Plant, China: World’s biggest artificial cave

The 816 Nuclear Plant is an unfinished underground nuclear weapon facility in the Fuling District of Chongqing, China. Hidden in the mountains and surrounded by dense forests, the complex has a secluded and secretive setting.

How big is the 816 Nuclear Plant?

The 816 Nuclear Plant is widely recognized as the world’s largest artificial cave, encompassing an area of over 104,000 square meters. The facility includes a network of tunnels and chambers that stretch for more than 20 kilometers and are 79.6 meters in height. It is designed to house nuclear reactors and associated infrastructure.

Constructed in 1966 during the Cold War era, the 816 Nuclear Plant was initially built to produce weapons-grade plutonium to enhance China’s national defense. Construction involved more than 60,000 engineering soldiers over 17 years. However, due to changing political climates and strategic decisions, the project was never completed or operationalized. In 1984, the plant was officially decommissioned and remained a state secret until 2002, when it was declassified.

The 816 Nuclear Plant has been open to the public since 2010, following over 25 years of closure. It primarily attracts history buffs, military enthusiasts, and those fascinated by Cold War relics. The site offers tours that delve into the plant’s history, construction, and intended use. The sheer scale and complexity of the underground tunnels and chambers and their historical significance provide a unique experience for visitors.

The 816 Nuclear Plant is the world’s largest artificial cave at over 104,000 square meters.

7. Sistema Sac Actun, México: World’s longest underwater cave

Sistema Sac Actun is located in the dense jungle along the Caribbean coast of the Yucatán Peninsula in Mexico, near the tourist-heavy areas of Tulum. It was discovered in 1987 and is part of the more extensive Quintana Roo Speleological Survey.

How long is the Sistema Sac Actun?

Sistema Sac Actun is the world’s longest underwater cave system, including connected dry caves stretching over 386 kilometers. In 2018, it was determined that the Sac Actun system was connected to the Dos Ojos system, significantly extending its known length.

This underwater cave system is renowned for its crystal-clear water and intricate network of passages and chambers. The caves were formed by the dissolution of limestone over millions of years, creating a vast labyrinth of submerged tunnels. Stalactites and stalagmites are prevalent throughout the system, adding to its stunning underwater scenery. The cave is also of archaeological importance, with numerous ancient Mayan artifacts and human remains discovered within its depths, providing insights into the region’s history.

Sistema Sac Actun is a major draw for divers and adventure seekers. It attracts thousands of visitors annually, particularly those interested in cave diving. Specialized tour operators offer guided diving excursions, catering to experienced divers and beginners. The cave’s remarkable visibility and unique formations make it a prime destination for underwater photographers and researchers. However, access is regulated to preserve the cave’s delicate ecosystem and archaeological sites.

Sistema Sac Actun is the world’s longest underwater cave system stretching over 386 kilometers.

8. Kazumura Cave, Hawaii: World’s longest lava cave

Kazumura Cave is located on the Big Island of Hawaii, near the town of Hilo. It lies on the eastern slopes of the Kilauea volcano, one of the most active volcanoes in the world. The earliest records of the cave were in 1966 when it was used as a fallout shelter.

Kazumura Cave is the world’s longest and deepest lava tube, extending over 65.5 kilometers and reaching a vertical depth of 1,101 meters. Its significant length and depth make it a significant geological feature of the island.

How was Kazumura Cave formed?

Formed by lava flows from the Kilauea volcano about 500 years ago, Kazumura Cave is a prime example of a lava tube. The cave features a variety of geological formations, including lava stalactites, lava falls, and unique flow structures that illustrate the dynamic processes of volcanic activity. The cave’s interior is characterized by smooth, undulating surfaces created by the flowing lava and areas of jagged rock where the lava cooled rapidly.

Kazumura Cave is a fascinating destination for geology enthusiasts, adventurers, and tourists interested in volcanic activity. The cave is privately owned, and access is restricted to guided tours to ensure safety and preserve the cave’s delicate environment. Each year, the cave attracts a modest number of visitors, primarily those with a keen interest in volcanology and speleology. The tours offer a unique opportunity to explore one of the world’s most extensive lava tubes, with highlights including traversing the intricate passageways and observing the stunning lava formations up close.

Kazumura Cave is the world’s longest and deepest lava tube, extending over 65.5 kilometers and reaching a vertical depth of 1,101 meters.

9. Blue Grotto Cave, Italy: World’s most famous beautiful sea cave

The Blue Grotto, or Grotta Azzurra in Italian, is located on the island of Capri in southern Italy. This sea cave is situated along the island’s northwest coast, near the town of Anacapri.

How do you enter the Blue Grotto?

The Blue Grotto is 54 meters long, 25 meters wide, and 150 meters deep, with a sandy bottom. The cave’s only entrance is 2 meters wide and 1 meter high at low tide, making access possible only by small rowboats and during calm sea conditions.

What makes the Blue Grotto so beautiful?

The Blue Grotto is a famous cave for being one of the few sea caves in the world with dazzling blue light. This light is a result of sunlight passing through an underwater cavity and shining through the seawater. This phenomenon creates a brilliant blue reflection that illuminates the cave as if there is an artificial light system underneath. Inside, the cave walls are smooth, and the water is crystal clear, enhancing the magical ambiance.

The Blue Grotto is one of Italy’s most famous tourist attractions, drawing hundreds of thousands of visitors each year. Tourists typically access the cave via boat tours from the main ports of Capri. The target audience includes international tourists, history enthusiasts, and nature lovers captivated by the unique visual feast here. The best time to visit is midday, when the sunlight creates the most intense blue reflection. Despite the cave’s small size, its unparalleled beauty and the enchanting experience of entering by boat make the Blue Grotto a must-see for visitors to Capri.

The Blue Grotto is famous for being one of the few sea caves in the world with dazzling blue light.

10. Waitomo Glowworm Caves, New Zealand: World’s best bioluminescent cave

The Waitomo Glowworm Caves are located on the North Island of New Zealand, near the town of Waitomo. This region is renowned for its limestone caves and rolling green hills.

The Waitomo Cave system includes multiple caves, with the Glowworm Cave stretching hundreds of meters. The main cavern, known as the Cathedral, is 40 meters long and 14 meters high, creating an expansive and awe-inspiring space.

What makes Waitomo’s caves glow?

The Waitomo Caves are formed from limestone, created over millions of years from the skeletal remains of marine organisms. Water erosion has sculpted intricate cave formations, including stalactites, stalagmites, and limestone shafts. The highlight of the Glowworm Caves is the bioluminescent worms (Arachnocampa luminosa), a species found exclusively in New Zealand that adorn the cave ceiling. These glowworms emit a bluish light, creating a starry sky effect that is both mesmerizing and unique.

The Waitomo Glowworm Caves attract around 500,000 visitors annually. The target audience includes nature enthusiasts and those drawn to the unique spectacle of the glowworms. Guided tours include a boat ride through the Glowworm Grotto, where visitors can glide beneath the twinkling glowworm ceiling. The cave is also part of a more extensive network of attractions in the Waitomo area, making it a focal point for tourists exploring the region. The natural beauty, unique bioluminescence, and educational value make the Waitomo Glowworm Caves a premier tourist destination in New Zealand.

The Waitomo Glowworm Caves have bioluminescent worms emitting bluish light, creating a starry sky effect.

Which fascinates you most?

Each of these incredible underground worlds offers a unique experience, from the massive size of Son Doong Cave to the enchanting glow of Waitomo’s bioluminescent chambers. Whether you’re drawn to geological marvels, historical significance, or sheer natural beauty, these top 10 most famous caves showcase the planet’s hidden treasures.

Plan your next adventure and discover the secrets beneath the earth’s surface. Share your thoughts and let Oxalis know which cave tops your must-visit list!

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