I'm wondering if some new through trip linkup in Gwydyr mines.
For Parc mine there are all sorts of plausible trips on paper, at least, starting from the level 2 portal. A through trip, exiting from level 3 is straightforward, if a tad wet. More interesting exit points would be out via Llanrwst mine or Cyffty mine. The former may well be impractical as the Llanrwst deep adit (LDA) had numerous blockages years ago and time probably hasn't been kind. A while ago I pondered whether it might be practical to exit from one of the Llanrwst shafts given that progress has been made climbing in the stopes behind new shaft to get on the same horizon as LDA but I feel that the upper workings are so unstable that any attempt would be suicidal. I think the collapse of diagonal shaft a few years ago gives a clue to the potential problems.
A through trip from Parc level 2 to Cwffty mine and out would be interesting but needs work on the Cwffty end to find a way to the surface. The engine shaft has a heavy grating (for obvious reasons) and the old adit probably has numerous collapses and a hostile landowner. There is a shaft which might connect which has a 'modified' bat castle which might provide an exit ;D
As it stands a trip to the upper levels of Cwffty from the level 2 portal and back makes for a long and very wet day - I did it with Roy and Jason quite a few years ago. I am not sure what state the ladder ways and ropes in Cyffty mine are in now - some bits where getting marginal then and time/weather may have taken its toll...
Of course it is still possible for do a through trip in Pandora's, but again the landowner is hostile and the environment agency are concerned about the metal level in the outfall. CAL couldn't put this mine on the list due to issues with the landowner (even though the entrance/exit is probably OK.
Dave