What’s the most interesting thing you have seen while exploring a cave system?

Question: What's the most interesting thing you have seen while exploring a cave system?
- Keywords:
  career,
  cave,
  personal,
  preference,
  work
Asked by 428bera39 to Kevin on 10 Nov 2014.
- Kevin Motherway answered on 10 Nov 2014:
  
  In Mitchelstown caves (in Tipperary – go figure) there is a huge open area, big enough for a symphony orchestra to be seated. It is the most amazing acoustic environment with sounds reverberating with such clarity and echoes. Thats pretty cool.
  
  The stalagtites and drip stone formations are pretty amazing too. well worth a visit.

Question: What's the most interesting thing you have seen while exploring a cave system?