A bus ride out of Donetsk gets you to Soledar, a small town famous for salt mining. Our tour kicked off with a ride down an elevator 300 meters or so (about 1000 feet) to a closed section of the mine. This was the first moment in my life where I realized I might be a bit claustrophobic.
The final cavern was 40 meters tall (131 feet) and housed a soccer field.
Pratt & Marmot