Since the topic of GoPros has come up, I'd like to share my underground video camera rig. My gear is a number of years old now and probably ready for an update. That said, the philosophy of the setup is still valid and it takes great video.
The camera is a GP-8 housed in a Ulanzi cage. The cage provides additional protection, and more importantly, the ability to mount a clear filter in front of the lens. If I scratch the filter, I can screw it off and throw on another one. Not so easy when I scratch the camera lens. It also has a battery door with an opening for a USB cable which solves the battery life problem.
The light panel is an Aputure F7 which provides an amazing amount of light. It also has color control so you can dial-in the color temperature you like.
We are underground for hours at a time and I'm running the camera for much of the time. Rather than carrying around a bunch of batteries, I use a Andecine battery plate with a NP-F900 battery. That powers both the GoPro and the light panel so I never run out of power. I may need to change chips, but not batteries.
All of that is mounted on a cheap 'C' handle that costs $15 all over Amazon.
This setup has worked amazingly well considering the places I've taken it.
Abby Normal