Anyway our trip was to check the apparent high CO2 levels in the cave, and also see if there was divable water down the back as Damian felt there might be.

Participants: Damian, Stan, John Dalla-Zuanna and Trevor Wynniat from Forestry SA. On arrival we lowered a gas analysing tube attached to a Cardiocap anaesthesia monitor down the hole. This gave initial readings of 20% O2 and <1% CO2...all OK so far. Damian went down the solution tube first and pushed the sampling tube down ahead of him. Deeper inside the CO2 jumped to 4-5% and O2 dropped to 16%...not so nice. Donning SCUBA tanks, Damian and I pushed further down the slope. A brief sniff of the air further in evoked a slight smell of putrefaction and the possibility of another gas being present. Even that slight smell made my head spin a little and I started to think about exiting the cave. Suddenlyn in front of me Damian became quite distressed, yelled "get out" and came charging past me out of the cave! I didn't need to be told twice and quickly followed. By now I was panting hard and sweating profusely, and Damian was the same but even worse. We made our way to the bottom of the chimney then exited the cave via the wire ladder.

I suspect that in the absence of face masks we both inhaled a fair bit of cave gas through our noses, causing acute hypercapnia...a very unpleasant sensation. Also there is the possibility of another poisonous gas in the cave like H2S2. 

Worst of all my watch strap broke in the cave and the watch remains there now. Little chance of finding a companion to come back and find it with me! I don't think there will be any more permits issued for this cave!