This seems like a Christic dream to me. Something is being sacrificed for the greater good...within you. Water is life-giving and may symbolize Spirit. The water is moving and this is an auspicious sign. You can't quite see what is being sacrificed, there is a veil there, but it will be clearer in the future, perhaps even through dreams. This sacrifice will lead to a resurrection. Green is a life-giving color, and blue may symbolize the spiritual realm. You are deep within the unconscious as symbolized by the cave...often a place of spiritual rebirth.
