You will no doubt have noticed by now the striking similarity between the cave’s entrance and a keyhole. The tunnel likely started forming underwater hence the rounded pheratic appearance of its upper portion and later wearing by running water would account for its more trench-like appearance lower down.
My caving partner e-mailed me a picture of the waterfall found deep within the passages beyond the sump. We are to say the least “totally pumped” for a more comprehensive exploration and photo session within the next few weeks.
There was once a theory that had been built around the results of a dye tracing experiment that suggested that these tunnels were in fact the overflow outlet of a large, well known system whose entry shafts are situated a few kilometres away.