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Postojna Caves (Postojnska jama) are the longest cave system in Slovenia. Located 31 miles (50 kilometres) south of Ljubljana, just 0.62 miles (one kilometre) from the town of Postojna, the caves are in western Slovenia, near the border with Italy and the city of Trieste.

Tiny stalactites on ceiling of Spaghetti Hall
Tiny stalactites on ceiling of Spaghetti Hall
Photo © Barb & Ron Kroll

Carved by the the Pivka River, over thousands of centuries, the Postojna Cave System is 13 miles (21 kilometers) long and includes Otok Cave, Pivka Cave, Black Cave and Planina Cave, as well as Postojna Cave.

Cave train

You can tour the dry sections of the Postojna Cave, daily, year-round. Bring warm clothing or rent a cape at the entrance, because the temperature inside the cave is a constant 48 degrees F (nine degrees C).

A 10-minute electric train trip brings you from Postojna Cave railway station, through a tunnel, into the cave. Passengers view The Conference Hall, which is large enough to host meetings and concerts.

The walls are black in the first section of Postojna Cave. During WW ll, Germans stored more than 1,000 drums of gasoline in the cave, which they used as a bunker. Partisans blew up the fuel, leaving black soot on the stalactites and stalagmites.

Rust colored, fin-shaped stalactites
Rust colored, fin-shaped stalactites
Photo © Barb & Ron Kroll

Cave tours

The dark walls give way to a subterranean fantasyland of calcite speleothems, shaped like fins, curtains, organ pipes, canopies and huge columns. Many of the limestone formations bear names, such as the Turtle, the Curtain and the most famous stalagmite, the Diamond.

At Great Mountain, you get off the train and meet your guide for a walk into the cave. Guides speak English and several European languages.

Postojna Cave tours last 90 minutes and cover nearly one mile (1.5 kilometres) by foot. Smoking, photography and eating are not allowed in the cave.

Stalactites and stalagmites

Strategically placed lights illuminate the cave formations and enhance their colours. Some stalactites and stalagmites are rust colored, from deposits of iron oxide. Others are cream colored and beautifully translucent.

Stalactites and stalagmites are formed when water, in the rock above, dissolves calcium carbonate as it seeps down toward the cavern. As water drops from the cave roof, it leaves a deposit, which eventually becomes a stalactite. When water drops land on the floor of the cave, the deposits build up stalagmites.

These formations grow at the tremendously slow rate of 1/25 inch (1 mm) in seven years. When you look around and see stalactites and stalagmites seven feet (two meters) in diameter and up to fifty feet (15 meters) high, it's obvious that the caves must be very old.

No one knows their exact age. Old graffiti at the entrance documents visitors to Postojna Caves as early as 1213.

Subterranean river

One room, the Dance Hall, has a huge crystal chandelier hanging from the ceiling 100 feet (30 meters) above. Another room, the Spaghetti Hall, has millions of delicate "spaghetti" stalactites growing from the ceiling.

Stalactites and stalagmites in cavern
Stalactites and stalagmites in cavern
Photo © Barb & Ron Kroll

Here and there, you catch glimpses of a green subterranean river gushing below your path. It is the same river that flows through the nearby city of Ljubljana. This river flows underground in two other places as well. Each time it emerges, it has a different name.

Postojna Cave history

Remains of Ice Age animals were found in Postojna Cave. Early visitors blackened the walls with their torches and left their signatures on the walls.

The first map to Postojna Caves was published in 1748. Famous visitors, documented in the Postojna Notranjska Museum, included Emperor Franz Joseph I.

Postojna Caves opened for public tours and started a visitors' book in 1819. The first cave train was added in 1872. In 1884, electric lighting replaced candles.

By 1893, cavers and scientists called Postojna the longest cave in Europe, after discovering eight miles (13 kilometres) of passages.

Cave life

More than 80 land and water species live in Postojna Cave. You can learn about them in the Proteus Vivarium, a speleobiological laboratory and station, open daily near the Postojna Cave entrance.

Visitors to the Vivarium see multimedia shows and examples of karst species and learn about their protection. The drobnovratnik (meaning "tiny necked") beetle was the first subterranean species discovered in Postojna Cave in 1831.

Olm amphibians (human fish
Olm amphibians (human fish)
Photo © Barb & Ron Kroll

Human fish

The largest and most famous cave animal in Postojna Cave is the olm (Proteus anguinus), called the "human fish" due to its pale skin.

Lizard-like olms stopped their development in mid-evolution. Although they are amphibian, they never reached the stage where their gills converted to lungs (as in frogs).

These endangered white salamanders can live for 60 to 70 years. They have eyes, but only use them to distinguish between light and dark. The snake-like creatures have elongated pear-shaped heads. Averaging about a foot (30 centimetres) in length, olms have an excellent sense of smell and hearing to cope with their dark habitat.

Things to do in Postojna

Near the Proteus Vivarium is the Postojna Tourist Information Centre and Visitors Center, with information on things to see and do in the Karst region, near Postojna Cave.

Of the 7,500 karst caves in Slovenia, 20 are open to visitors. After touring Postojna Cave, you can visit Predjama Castle, the cave below Predjama Castle, Pivka and Black Cave, Military History Park and the reconstructed Modrijan's Mill next to the Pivka River.

Hotel Jama is located in Postojna Cave park.


Postojna Cave: www.postojnska-jama.eu

Slovenian Tourist Board: www.slovenia.info