One of the "cool" things about Linville Caverns is the temperature. Inside, the caverns remain 52-degrees year-round. A lightweight, preferably waterproof, jacket is recommended.
It's important to choose appropriate shoes for touring the caverns. Slick soles or heels won't cut it inside the mountain. The paths are easy to navigate, but remember, there's dripping water so it can be slick in spots.
Speaking of the pathways, the tour is wheel chair accessible, with only a couple of places unavailable to wheel chairs. Kids are welcome, but strollers or backpack carriers are not permitted. Front kid carriers are allowed.
To preserve the caverns and protect the mineral formations, look with your eyes not your hands. (Said in my best teacher voice)