Comment by adriand
I truly don't understand the appeal. What is enjoyable about this experience? I like risky and athletic stuff and have done a bit of climbing (nothing technical) and the appeal there seems quite obvious - in addition to the adrenaline rush, you've got clean air, beautiful vistas and scenery, etc. A pitch-black, dank hole in the ground - ugh. The thought of getting lost, especially getting lost and losing illumination, seems like the ultimate nightmare. On the plus side, those big caverns with various mineral formations do look quite spectacular. But you tell me, what's fun about this?
For me, it was the challenge and allure of doing something relatively difficult and rare. The first time I saw a Stop - Prevent Your Death sign[0] at depth, I knew I wanted the training to go beyond it.
It's also really peaceful underground.
Amusingly enough, I can't handle blue-water or wall dives (vertigo), nor wrecks (those aren't supposed to be there!), but caves are no problem. You've got walls, floor, and ceiling as a frame of reference, and everything is nice and cozy. It's like the Earth is giving you a hug.
[0]: https://commons.m.wikimedia.org/wiki/File:Vortex_Spring_cave...