I remember reading about the spring as a child due to the artifacts found in its depths. However, as I arrived it wasn't an archeological interest that grabbed me it was all the old people trying to feel better. As you entered the smelly water ( it is a mineral spring) you begin to walk in a circle around the sink hole with the (old people) trying to feel better. You'll notice that they are all smiling and chatting in Russian, Chech and Polish English is not the norm. It's something to experience it's warm and social I felt better when I left, I stunk but I felt better. I skipped yoga, at 51 I was probably one of the youngest there I didn't want to get shown up.
If you stay at Mineral Springs Motel you get a discount, I highly recommend it for the experience.