The easiest way: take a tour
A tour from Ljubljana picks you up and gets you to the cave for your slot, and most include the entry tickets. Most also take you on to Predjama Castle, which is otherwise awkward without a car because the shuttle between the two only runs in season. There's no timetable to juggle.
Ljubljana: Postojna Cave & Predjama Castle Tickets and Tour
The standard half-day package: transport, both entry tickets and a guide to handle the timings. Good if you do not want to juggle trains and the seasonal shuttle.
Check price & dates on GetYourGuide (opens in a new tab)Postojna cave day tour from Ljubljana
For people who only want the cave and would rather skip the castle.
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Going on your own
By car
Take the A1 motorway south-west towards Koper and leave at exit 41 (Postojna). The park is about 2 km from the exit and there's a large paid car park at the entrance. The drive from Ljubljana takes under an hour. With a car you can also get to Predjama Castle in minutes.
By train
Postojna is on the main railway line from Ljubljana towards the coast. From Postojna station it's about a 25-minute walk to the cave park, and a local bus links the station, the bus station and the park. Check times with Slovenian Railways (SŽ) on the day you travel.
By bus
Intercity buses run regularly from Ljubljana bus station to Postojna. Some go right to the cave park, while others stop in town, roughly a 20-minute walk from the entrance. Check which stop your bus uses when you buy the ticket.
Combine it with Lake Bled or Piran
Short on days? These tours fit the cave into a longer day with Lake Bled or the coastal town of Piran.
From Ljubljana: Lake Bled & Postojna Cave with Entry Tickets
The two most-visited sights in Slovenia in one long day. You spend less time at each, but only one day travelling.
Check price & dates on GetYourGuide (opens in a new tab)From Ljubljana: Postojna Cave, Predjama Castle, & Piran Tour
Goes on from the cave and castle to the Venetian-style harbour town of Piran on the coast.
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Common questions
Is Postojna Cave worth it as a half-day trip from Ljubljana?
Yes. It is one of the easiest day trips from the capital. You can go in the morning, see the cave and the castle, and be back in Ljubljana by late afternoon.