......Has the underground bit been explored before?
Lowest level at Gilfach was wet (fairly deep but below cockles), walk-in. Middle level shaft accessible for an SRT trip with walk out on lower level. I think a channel was dug to lower the water level a bit about ten years ago (so if not maintained it will have gone up again). No idea about the upper level
Cwm Ciprwth adit is a walk in passing a flooded whinze on to a couple of blinds (so Cwm Ciprwth workings all flooded).
It's a shme that they didn't replicate the shaft headgear as well
The restored flatrods, counterbalanced pump head and waterheel assembly, as captured so well by @HughieD above are the real draw. The intact friction cluth for the winder can just be seen on photo 10 above