SH 799 125
A toughie to find – it is marked on the O/S map as a quarry and Levels it is located near Dinas Mawddwy, Mid-Wales. You can park right next to it but you need to drive along forest tracks (no gates).
All ungated, no known permissions required
possibly ¾ mile in total or more
There is water in the main level but no evidence it has ever been higher than 1 foot deep. There is a trial adit higher up that is flooded almost to the ceiling.
Hendre Ddu is a large quarry on multiple tiers stepping up at the back end of a “V” valley. There are numerous tunnels and adits on many levels on the outside of the quarry which was used to transport the quarry material.
HOWEVER, at the front of the quarry (marked as “levels” on the O/S map) and to the right as you approach the quarry is a large adit around ½ mile (or more) in length. This adit contains a good number of chambers and a higher internal level/adit can be reached internally by scrambling up the spoil in one of the chambers.
The main adit is mineral rich with sulphur & iron as you enter although this disappears as the slate manifests.
The chambers are in poor condition which some substantial collapses.
There is an interesting tipping arrangement from the higher level with some equipment left in situ above the tipping hole which can be seen when you work your way up.
Additionally, on the upper level there is a small hole in the main adit leading into a small chamber with an internal stream of water pouring down the wall which is bright yellow with sulphur (the photos don’t do it justice) – this is a real spectacle and much better to see with your own eyes (it’s not the usual zinc/brown colour – it really is bright yellow and fantastic).
Plenty of chambers to mooch around in.
I have been unable to find any references to this mine and it may be largely forgotten about.
One higher adit which could not be reached – it is not know where it leads.
Release the Kraken .....