The Cave is breathing - Day 4Video | Updated 3 years ago This video explains why the caves breath in and out. Transcription As you can see the cave’s breathing in. Today, it’s breathing in fairly strong. The reason why you get the cave breathing in is you have a pressure differentiation in between the cave – inside the cave – and the air pressure outside the cave. So at the moment we’ve got air pressure outside the cave increasing, so the air is being drawn into the cave. Conversely when there is a low pressure system outside, it’s breathing out. We know the calcite decorations in there is roughly four million years old. There have been some phases of growth, the last was about 300,000 years ago, and during that time there’s been quite a large amount of collapse in one section of the cave. View the discussion thread.