One of the highlights of my trip to Budapest (in August of '99) was the caving experience. Budapest has numerous caves in Buda hills. Matyas Cave is the second largest cave in Hungary. It is in the Buda Hills and you go down about 220 meters all the way to the Danube level. The whole trip takes about 3 hours. 1.5 hours down and 1.5 hours up. You wear a special suit and a helmet with light. It is completely dark in the cave.
The temperature in the cave is the same all year round, in the 50's Fahrenheit. In other words, it doesn't matter what time of the year you are in Budapest. I suggest wearing just a T-shirt and shorts underneath the suit, because you are going to get hot from all the physical activity, and you are going to sweat a lot. Also, very important, wear old clothes. Don't put nice new sneakers on. They will get dirty. Also, don't take a watch, camera or any other gadgets.
Caving is certainly not for claustrophobic people. There are several ways inside the cave, some easier and some...well just enough space to squeeze the helmet in. There are quite a few narrow stretches and in many places one has to use his/her physical strength. There is a 12 meter stretch, called the "Sandwich of Death," where you crawl on our stomach. There is very little room; I could barely squeeze my helmet in. It was a good challenge, and I felt very good that I did it. It was the hardest part of that cave.
Another good challenge that our guide convinced us to do was to go without light. The last 36 meters of the cave on the way up we (a group of 7) all turned our lights off and held each other by the ankle and crawled in complete darkness. This was awesome!
There is no caving experience necessary. This was my first time, but definitely not the last! If you need more information, contact Backpack guesthouse (there are a few hostels that run caving trips, but I just have a postcard with Backpack's number) (36-1) 385-8946 (Don't forget to use international phone service!).
The cost of the trip (as of August '99) was about $10. Maybe even less. What a bargain!