the open stope in Llanberis (probably Yew Tree), we bolted a route at one end which was probably clear of anything loose, apart from anything dislopded by the wet weather stream that comes in round a corner. This gave a good free hang, unlike routes we spotted hangers left on which seemed to be down the wall in the middle of the stope. Our aim on that trip was to descend from the end of a level you can swing off intio, part way down (about 20-30m from memory, need to check our survey). This involved a sloping descent which after a lot of gardening and a few bolts (& we didn't have a drill so all put in by hand) entered the roof of an impressive stope. A bit more gardening & bolting was required but we ran out of time & havn't returned, due to circumstances rather than any wish to do so. This was probably 6 (or perhaps quite a few more) years ago. No sign of previous post-mining exploration of that bit then. Has anyone been further? If anyone does, only request is please please please do a proper survey & let us see a copy (gradually getting together a survey of everything accessible). We also started some projects to extend exploration off the "tourist" SRT route in the SE section.
Incidently we initially had permission from the CEGB who seemed quite happy for access, but obviously the site has changed ownership quite a few times since, anyone aware of the current situation (there have been various issues re climbing access at Dinorwic).