Day 102: Postojna Caves

JULY 14 - Start the day early by walking into town, buying a train ticket for our next destination in a few days, and collecting a rental car we will use for the next two days. The bus station is already hopping at 7:30, backpackers cramming into the regional destination buses.

We head southwest to the town of Postojna, on the road to Piran and Trieste. This part of Slovenia is the ‘Classical Karst Region’, which refers to the thick limestones deposited here in the Cretaceous (145-66 million years ago). It has given its name to the distinctive geology called ‘karst’, in which limestones are dissolved by water over time and develop underground rivers, caves, collapse features, and steep valleys.

We visited a karstic cave system in the Czech Republic on Day 82. The one is Postojna is significantly larger, at least the portion available for viewing. We saw about 3 km of a 24 km long cave system.

A photo showing columns, stalagmites, stalactites, and some dripstones.

The tour of the cave was about 1.5 hours and involved a 10 minute underground train ride, following by a long footpath with guide. This is a very popular tour, they push at least 400 people through here per hour. This is touted to be the only underground cave train ride in the world. Having worked underground in a gold mine and ridden ore trains for two years, I think that claim is splitting hairs a little.

All dripstones.

A photo from the ‘Red Cave’, where iron oxides have tinted the speleothems.

No creatures in the pool, though we see some later in the ‘cave zoo’.

From the ‘White Cave’, showing a large number of small stalactites.

After the cave itself, we went to the vivarium. This was a big hit with Odette, and the only zoo I’ve been to that is housed inside a cave. The biggest animals here are the olms, or cave salamanders, which can grow up to 30 cm in length and live up to 100 years. They are blind and very sensitive to light, hence impossible for us to get photos of. When they were first seen by people (after having been washed out of caves during floods), they were fancifully thought of as baby dragons. At the time there was no understanding that some animals live in complete darkness.

FUN FACT: Postojna Caves hosts the largest biodiversity of any cave system in the world. It even has the only known cave mollusk.

Did get photos of other creatures, including some silverfish-like insects from the order Zygentoma.

The slenderneck beetle.

Map of the Postojna cave system. Many of the caves represent old river courses that eventually dried out as the river found its way through deeper passages. Dried out underground river courses, over time, developed the rich display of speleothems shown in the above photos.

On to the Karst Museum, with plenty of interactive stuff for kids (and adults) to learn about caves. There is plenty to do in there for an hour or so.

Leave Postojna Caves and drive for about 9 km up a valley to Predjama Castle. The Slovenian word for cave is ‘jama’, so this refers to the fact that the castle was built in the mouth of a cave.

The original castle was fully inside the aperture and very well defended against any attacks. It was extended in later centuries when it became a residence during less warlike times.

Of the castle’s inhabitants, the most famous is Erazem of Predjama. By the time we got to this castle, I had heard the story of his incarceration in Ljubljana Castle, escape, and ignominious death on three separate occasions. It seems that legends have grown around his life, as he was something of a ‘robin hood’ castle lord.

A wall of the original castle, much older than the exterior shown in the photo above. Besides the ability to collect a lot of water from the natural cave walls, passages behind the wall shown could access secret exits far away from the castle. These passages were crucial to obtaining food during long sieges.

The old part of the castle, as seen from the inside.

There is an underground river than flows into the cliff wall, underneath the castle.

Slovenia