It is fine to explore, but some things should be left for better moments when you need to find shelter during a survival situation.
A cave is an obvious shelter for difficult times; instead of building your own survival shelter, if there is a cave anywhere near your position, you could simply slip in there and be relatively comfortable. There are many different caves and some constitute very complex and extended systems, and there are also mines constructed by men which could serve very well in a similar way. For the purpose of this article, a cave and a mine will be considered similar.During any sort of survival situation or emergency a cave provides a very convenient shelter but of course, caves could be dangerous for a number of reasons, especially for those who have no experience in potholing.
Don't explore when you are just surviving.
Thus, while a cave could be useful, survivors should always assume that they are potentially dangerous.Out of curiosity or the need for resources, if a group of survivors stay inside a cave for a little bit of time, they will start to explore it. This should be done with extreme caution, and as a first rule, everybody there should be informed at all times about the intentions and whereabouts of the others. There are then two main reasons not to use the resources available in the cave and preferably go outside, into the woods or whatever it is outside it:
Resources inside the cave will be usually limited; wood, for example. If you use all the flammable materials found inside the cave just because you don't want to walk outside a little longer and further, you will deplete whatever is found inside the cave pretty soon. Use those resources as a reserve, instead. Moreover: you could use the cave's interior as a storage depot and bring in additional supplies and reserves such as wood, water.
The risk of getting hurt will be diminished; walking outdoors is usually safer than doing the same in a dark place with uneven ground under your feet. Outside the cave you will know at least and in most cases, what is under your feet.