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The architecture, history, and healing waters of Budapest, Hungary have earned the city a reputation as one central Europe’s most fascinating urban environments. While our last blog explored the wonders of the city’s ancient thermal baths, we’ve barely breached the surface of Hungary’s magnificent geological formations. 

Beneath the cover of Hungary’s grassy hills and limestone mountains is a network of subterranean caves that stretch nearly 30 miles. Carved by the ancient waters that once coursed through the country, the design of Hungary’s present-day cave system is both complex and marvelous.

Visitors to central Europe can traverse millions of years of geological history as they walk or swim through the country’s numerous cave systems. From the Caves of Aggtelek Karst in the north and the Tettyei Tufa Caves in the south to the diverse collection of underground chambers in Budapest, Hungary contains one of the largest cave systems in Europe.

Today, Budapest is home to over 120 geothermal springs and dozens of baths that are heated by their proximity to the Earth’s core. As this naturally heated water flowed through the geological landscape millennia ago, it carved paths through limestone and existing rock formations. Making the city home to the largest collection of thermal caves in the world!

Molnár Janos is known among divers as one of the most extraordinary cave systems in the world, yet many of the city’s inhabitants do not even know the cave exists. The underwater tunnels were discovered in the 19th century by its namesake, Molnar Janos, who traced warm spring waters from an outside lake to its source beneath the city. Yet expert divers only began exploring the cave in the 1950s, charting nearly 4 miles of tunnels over the past 70 years. Since its discovery, miles of rope has been laid for adventurous explorers to find their way back to the exit. Though the cave contains many small chambers, the largest room is said to have the capacity to hold over 350 double-decker buses!

What can we learn from underwater caves? 

The limestone composite of Budapest developed approximately 30-50 million years ago, during the warm and humid Eocene period. Paleontologists believe that around the same time, contemporary mammals began to develop. As a result, the features of a cave’s walls and the calcium impressions found there offer fascinating stories about mammalian evolution.

In her Ted Talk, Underwater Cave Explorer, Jill Heinerth, explains that humans know more about space than the underground waterways coursing through our planet. As the first person to cave dive in Antarctic Iceberg, Henierth has undertaken dangerous endeavors to learn more about what she calls the ‘lifeblood of mother earth.’

Even in the most Urban of areas, you can still find some of nature’s greatest wonders. Far beneath city lights, homes, and urban structures, divers like Heinerth plunge into the darkness to map subterranean geological landscapes and study life underground.  Thanks to re-breathers, a scuba device that absorbs exhaled carbon dioxide and safeguards oxygen, divers can spend as many as 20 hours swimming the expansive caverns below ground level.  While diving, explorers encounter unusual animals who survive without pigment or eyes. Many of these life forms preexist the dinosaurs and can teach us a lot about surviving evolution! Geologists who work alongside Heinerth study the rock forms in caves to learn about ancient sea levels and changes in climate. Like the rings of a tree, a slice of rock can tell geologists the story of how landforms have changed over millions of years.

While visiting this central European gem, we opted for sneakers instead of snorkels and explored some of Hungary’s most popular dry-subterranean caverns.

Caves of Aggtelek Karst

The mountainous territory near Hungary’s north-eastern border boasts over 700 caves and 14 cave systems which first opened to the public in 1806. Located just two hours outside of Budapest’s city center, the caves of Aggtelek Karst give visitors the opportunity to connect with a rich diversity of structures that were shaped over tens of millions of years.

Dripstone caves: When rainwater absorbs high levels of carbon dioxide, it becomes acidic and can seep through limestone to enter the caves. As lime precipitation collects, dripstones (stalactites) are formed. Baradla-Domica, Aggtelek Karst’s most renowned cave system, connects Hungary to Slovakia and contains the world’s highest stalagmite (32.7m).  Richly decorated with stalagmites and stalactites, and the subterranean Styx River, Baradla-Domica is visited by close to 200,000 people per year.

While stalactites are icicle-shaped mineral formations that hang from the ceiling of a cave, stalagmites are the upward-growing mineral deposits that have precipitated from water dripping onto the floor of a cave.

Domica Cave. Photo by Jojo,Wikimedia commons, August 2006.

Tettyei Tufa

Near the southern border of Hungary and Croatia, is the city of Pécs.  The hilly city is full of old-world charm and contemporary class. With its shopping centers, Zsolnay fountains, elaborate artworks, and Mediterranean climate Pécs hosts plenty for travelers and students to explore. Though the town itself is a delight, the most fascinating part of our trip was experienced underground.

Tettyei Tufa Cave is a unique geological formation that was carved nearly ten thousand years ago. Tufa, a porous mineral rock, lines the walls of the cavern which spans nearly 2.5 miles.  In recent years, the cave has become a popular tourist attraction that hosts tours every hour. Guides tell visitors about the history of Tettyi which includes dragon lore the recounting of a time when villagers lived inside of the cave. According to records, families that could not afford the high taxes and housing prices above ground moved into the caves and lived there into the early 20th century.

Hospital in the Rock Nuclear Bunker Museum

Nestled within the industrious Castle Hill district of Budapest’s Buda neighborhood, is the Hospital in the Rock Nuclear Bunker Museum (Sziklakórház Atombunker Múzeum).  At the turn of the 20th century, the 6-mile stretch of interconnected caves was converted into a secret emergency hospital used during WWII and again during the 1956 Revolution.

The history of the emergency hospital indicates that underground caves and tunnels were fortified to serve as an emergency air raid shelter that would connect to Buda Castle.  The hospital, which was built to house up to 200 patients, overflowed with 700 soldiers and civilians who were injured by the violence of German occupation during WWII. Though the tunnel and cave systems were extensive, the fortified spaces of the hospital could hardly withstand the number of casualties from WWII and the 1956 Revolution.  Between 1958 and 1962, the “Hospital in the Rock – Secret Emergency Hospital and Nuclear Bunker” was expanded to withstand potential chemical and nuclear attacks during the Cold War.

The hospitals, homes, and exhibits that lay within the caverns of Hungary prove that Hungarians are an innovative people,  who repurposed some of mother nature’s most impressive compositions.

Marilyn Fordney and Alex Havasi visit the Bajot, Mount Oregk, Jankovich Cave in Hungary.

The Havasi Wilderness Foundation aims to expand conservation efforts, educate the next generation of environmental stewards, and encourage compassion for animals and the natural world. Help us achieve these goals by making a tax-deductible donation today.  If you cannot afford a donation, that’s okay— take a walk outside, investigate the world around you, and share with others the importance of caring for our planet.

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