A cave, being womb-like, may carry feminine symbolism.
1. For Freudians, a cave represents the female genitals.
2. It may also represent your mother; or your anima if you are a man.
3. A cave may represent a womb, a place of conception or birth. (It is a hollow place in Mother Earth. A Renaissance painting depicts the conception of Jesus in a cave, with a flash of lightning as the fertilizing agent. Here we see the almost universal symbolism of sky = father, earth = mother.)
The conception or birth represented in your dream may not be a physical one. Metaphorically, a 'pregnant’ situation is one that may ‘give birth' to something new, a new order of things. So it may be that something new is coming to birth - or trying to come to birth, if only the conscious ego will let it.
4. A cave may symbolize the unconscious. Wordsworth ('Prelude', Book III, lines 246-7) speaks of 'Caverns... within my mind which sun/Could never penetrate'. The unconscious lies beyond consciousness (of which the sun is a symbol) and is therefore 'dark' and possibly frightening. But we can allow the light of consciousness to penetrate the unconscious. Rock suggests permanence and antiquity. Similarly, the unconscious is a much more ancient part of the human psyche than intellect, much closer to the source of things.
5. If, in your dream, there is someone in the cave, it may be that he or she is a Wise Old Man/Woman figure see Wise Old Man/Woman), a personification of the wisdom contained in the unconscious. Perhaps he or she will let you into the secret of your 'destiny', or uncover for you the causes of whatever is troubling you or spoiling your life.
6. There may be a fierce-looking monster, snake or dragon in the cave. There may be treasure there, too, guarded by the monster. If so, the treasure is yourself - your true self - or the key that will unlock the secret of life for you. First of all, though, you must overcome your fear of the unconscious (the frightening monster). The terrifying thing in your unconscious may be some traumatic childhood experience that, being unbearable, was repressed - banished from consciousness. Like St George, you have to slay the dragon, overcome your fear of the unconscious, learn to trust it and let it serve you (which is what it is there for).
7. It may be that the cave in your dream represents a hiding-place, a refuge from life’s problems. If so, there will be other features of your dream(s) pointing towards this interpretation.
In dreams we may need to run back into our cave, (infantile dependence,) to escape the larger, fierce reality of every day life. On the other hand, if we fear the cave and its darkness, we may be expressing a lack of self-confidence about our ability to cope with the unknown. We need to analyze our behavior in and around the respective cave, to better determine the message related to us by our Unconscious. A simple assessment of the cave’s psychological implications can be determined in the climate of the cave itself. Is it warm and inviting, or cold, wet and mortifying?