Notranjska, land of caves, a vanishing lake and deep forest

Postojna and Predjama, the bit everyone sees

At 19.5 km, Postojna Cave is the longest cave open to visitors in Slovenia, and the tourist board rates it Europe’s busiest. Its underground train has run since 1872, carrying visitors deep into the hill, and the guided visit takes about ninety minutes. Inside lives the olm, a blind amphibian with a lifespan of up to a hundred years. At Christmas the cave stages a living nativity scene underground with more than 500 participants, according to the tourist board.

A few kilometres away, Predjama Castle has been built into a cliff for over eight centuries and holds a Guinness record as the world’s biggest castle inside a cave. The same company sells combined packages on its website and warns about resellers. My advice is to do the cave first thing and the castle around midday.

The town of Postojna, with 10,043 people, is the largest in the region and has most of the accommodation. The municipality took 113,003 arrivals in 2025, more than two thirds of the regional total.

What to see in Notranjska beyond the cave

Lake Cerknica is the largest lake in Slovenia at 26 km², and it is intermittent. At some times the plain floods and you can row or fish; at others it dries out and you cycle across it; in a cold winter you might skate. The tourist board counts over 270 bird species and places it within Notranjska Regional Park, one of three regional parks in the country. Cerknica also has one of Slovenia’s most colourful carnivals, with witches flying down from Mt Slivnica and the Butalci, the dimwits of Slovenian literature, taking over the town hall during carnival.

To the south, in the Lož Valley, is Snežnik Castle. Its lords are recorded in the 13th century, but what you see today is the hunting residence that the princes of Schönburg-Waldenburg created after buying the estate in 1853. The National Museum opened it in 2008 with genuine period furniture, an Egyptian room and generations of hunting trophies. For me it is the region’s real surprise.

The National Museum suggests rounding off the day in the Lož Valley itself, with the hunting collection and dormouse museum, the Martin Krpan trail, named after the Slovenian literary hero, and the European E6 long-distance path, which passes the castle. Križna jama, with its underground lakes, is close by. And to the east, Bloke, the region’s smallest municipality, has 1,563 people spread across 45 settlements, the largest of them, Nova vas, with 271.

Pivka and the intermittent lakes

Pivka offers two visits with nothing in common. The Park of Military History has a huge military collection and the submarine P-913, which you can walk through. The eco-museum of the Pivka intermittent lakes explains the 17 lakes that come and go around the area, the same phenomenon as Cerknica on a smaller scale. The Dina Centre for Large Carnivores rounds off a morning with children.

If you are staying the night, see the best hotel deals in Postojna for your dates: the well-placed rooms go fast.

Forests, bears and Mt Snežnik

Ilirska Bistrica is the second-largest municipality in the country, at 479.9 km², and stretches up to Mt Snežnik. Its beech forests, together with Ždrocle, form part of UNESCO’s ancient beech forests of Europe. The tourist board notes that Slovenia has a large population of wild bears and offers bear watching in the green Karst. If you walk in these woods, gov.uk points out that bears live in forested areas across the country, so read up on what to do before you go.

One, two or three days in Notranjska

With one day, Postojna and Predjama. With two, add Cerknica and Snežnik, both to the south. With three, add Pivka and a walk in the Ilirska Bistrica forests. I would do it by car, because the sights are scattered across forest and farmland, and the National Museum, for one, only gives directions to Snežnik by road.

If you are staying the night, see the best hotel deals in Postojna for your dates: the well-placed rooms go fast.