I used to do it in my teens. Living on the edge of the Peak District we had caves and old mine workings in abundance to explore. Our F E college had a small club and we would go out weekends in the summer - too wet and dangerous in the winter. Some of the things you see created by nature in cave systems are jaw droppingly beautiful. Couldn't do it now - some of the passages were a nightmare and I was as thin as a rake in those days. My mother used to have kittens every time I went. My own DD went a couple of times to Settle with an outdoor activities club she belonged to for a while, and then I knew just how my mother felt. I must say, I haven't seen the programme but I have the utmost admiration for these ladies. It takes stamina, and not a little strength, to negotiate some caves.