Slovenia - Skocjan Caves/Lipica or Postajna Cave/Predjama Castle/Lake Bled?

Skocjan Caves, hands down. It’s so unique among the world’s cave systems that it’s a UNESCO World Heritage Site. It has a river running through it that you’ll see as you cross a bridge high above it on the cave’s pathways.

I agree with Skocjan Caves - absolutely amazing. I did my tour with ToDoInSlovenia and it was a good tour. The stud farm was ok and would be more interesting if you were really into horses. It was nice to be on a small group tour that got you to/from the sights easily and gave enough time to see them. Enjoy your trip - that's an awesome RS tour!!

Try to combine Skocjan Caves with Predjama Castle!

If you are in downtown Ljubljana and comfortable with driving, picking
a car up and driving gives you more options and access.

Both Skocjan Caves and Postojna Caves are in the same general direction
so you can possibly visit them both on the same day.

There is (was) also a general city bus pickup from Ljubljana (CS) to Postojna
Caves, which might allow you to do a full-day's trip. But you probably need
a car to get to Skocjan from the endpoint of Postojna.

I agree with everyone here- Skocjan Caves were a highlight of our trip to Slovenia, I've never been anywhere else quite like it- you walk thru a small tunnel and come out into a huge cavern along a river. Good luck deciding.