Last time I looked this little tunnel was under water.
At the time that myself, Marcel, and his nephew visited the Rockwood area it was mid winter, there was a faint breeze coming out of this hole and small ice crystals were forming on the topside of the tube.
In Rockwood the strata dips downward to either side of the valley at a pitch of 7 degrees and it was for this reason that we suspected this tube might lead on to something deeper in. Water seeps down this hole (slowly) and in the direction that it initially leads off there is another valley about 300 meters away running parallel to this one.
Marcel squeezed in with only the soles of his boots filling the entire entrance and soon those were gone as well. The picture shows Marcel on his return journey. He managed to turn around inside. I guess at one time a significant stream used to disappear down here – the channel leading up to the depression would suggest that.
According to Marcel, there is a chamber some distance in – with well formed soda straws. The breeze is blowing from a hole in this inner chamber.
I would not fit down that hole and I would not even try. We had initially thought to approach the property owner with the idea of allowing us to dig to widen the entrance and tube. A significant amount of digging had actually widened the main caves in Rockwood to their present size (see my book Rockwatching for details on that)(You can only buy it second hand on Amazon now).