To apply some advice that I received several years ago, one hard drive will annoy ya….two are a paranoia. The hard truth is that only three things in life are certain: death, taxes and hard drive failures. They all have finite life spans. No matter how sophisticated your drives may be, given enough use over enough time, they will fail. Not if, but when.
To my knowledge, there are just five cave systems within our 59 national parks, at least those that are open to the public. While other caverns are found in some national monuments, let’s stick to these big 5 for now.