Trudging across the muddy track in a badly fitting jumpsuit and a helmet that knocks against my head, the guide stops at the entrance. On first impression it's not much to look at - a small door on a graffiti covered concrete bunker structure that lies against the base of the hill.
Inside, it opens up into a mine that connects with the cave system. The network running under Mátyás Hill is the largest in Hungary, a complex labyrinth of caves that can only be accessed via the mine shafts.
To enter the cave, I descend a ladder that drops down 10m straight, into a cavern named "the chapel", christened so after its former function.
Once in the system, the adventure starts by sliding down slippery tunnels and crawling through on hands and knees into smaller and smaller chambers.
It's cool in the caves at first, but the combination of the steady temperature, the jumpsuit and the warmth of physical exercise transform it into a sauna. 15 meters underground, when the group turn out the lights and listen, there is nothing. Pure silence and uncontaminated darkness.
The caves are used as a training ground for geologists and spelunkers, but for amateurs like us, each rock and hole pushes us to our physical limits.
Almost crying after 3 hours burrowing undergound, using muscles I didn't know existed, I feel the wind on my face near the exit.
Ascending the ladder I know the sun is nearly on my face, the air fresh again and a beer nearby. Tired, aching and eager to go again.