these caverns are absolutely stunning and a must see if travelling through New Mexico. The park will open at 8 am daily, i would get there before that and start walking at 8 as it does get very busy. Most guests opt for the self guided tours, it will take you a few hours to explore on your own. The walking is very easy, mostly downhill and paved or rocky. You will descend over 700 feet underground where the temperature remains in the high 50's year round. The views and rock formations are unreal. There are many opportunities to stop and take pictures as well as signs to educate you on what you are seeing. At the end of the walk you ill be taken back to the surface via an elevator. The whole experience is really great.