The Friends of Cwmorthin Slate Quarry

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Access for Experienced Individuals and Caving Clubs

Cwmorthin is freely available for anybody suitably experienced and equipped to explore either individually or as part of a club. The two entrances are both gated and locked with key-type padlocks. This system replaces the earlier combination-lock system that was receiving frequent abuse.

There is a 20 deposit required to borrow a key.

Keys can be collected one from one of the locations shown below. You will be requested to sign the key out with your name and key-number and leave your deposit. Please return it after your trip.

Locations where keys can be collected from

  1. Go Below Conwy Falls Office (Betws-y-coed). Open 7 days a week, 9am - 5:30pm.

Please familiarise yourself with the Important Notes below before venturing out to the mine.

Access for Novices and Beginners

If you've little or no experience with disused mine-exploration and wish to explore Cwmorthin, there are several ways to go about this.

  1. Firstly, consider actually joining the FOC and attending a few work days. We'll show you around a bit and find some jobs for you to do that are suitable! You'll meet other members who will be happy to bring you with them on future exploring trips.
  2. Secondly, you can join a local caving club or mining enthusiast group to come on some trips and gain some experience and friends in mine-exploration. Several friendly on-line communities exist such as, and all of whom will be welcoming and supportive. For a good local club try
  3. Thirdly, consider a professionally guided trip from They are a local business with experienced and qualified guides, who will provide all the equipment and take you to the mine for a trip. They are used to working with people who've never been underground before, but will ensure you get an excellent and exciting trip within your abilities that you might not even know you had.

Access for OEC's and Professional Groups

Sections of Cwmorthin are Blue-Route approved and annually inspected by a visiting Mines Engineer. They are therefore suitable for leading novice groups professionally by instructors qualified with either LCMLA Level 1 or Level 2, or CIC.

It is important that the leaders are familiar with the areas that are Blue-Route approved and in the case of LCMLA holders - that the mine is listed on their venue sheet. There is no need to apply for a permit.

The mine is strictly only available to non-profit Outdoor Education Centre groups and schools. Commercial or profit-making groups, even freelance guides, must have the approval of the FOC before using the mine for commercial group leading.

The mine provides an excellent venue for demonstrating Welsh Slate history as well as a good array of Level 2 pitches and traverses.

Important Notes for All Visitors (Please Read!)

If you intend to visit the mine, it is very important that you read and abide by the following set of instructions:

  1. Collect a key from one of the locations listed above on the morning of the day you intend to visit, and return it after your trip (not the next day please). a 20 deposit is required. Do not lend the key to anybody else or copy it.
  2. The mine is to be accessed on foot only from parking in the free Cwmorthin car park. Access by 4x4, trials bike or mountain bike is by prior arrangement only.
  3. When you unlock the mine and enter, it is very important that you lock it again behind you.
  4. Ensure that you DO NOT LOOSE THE KEY in the mine, for obvious reasons. Make yourself aware of how to get to the emergency-exit out of the smoke flue in case you find the lock inoperative whilst attempting to exit.
  5. Please do not install any bolts, ropes or other rigging anywhere in the mine without approval. We have a system of cataloguing such installations. This includes hand ropes, fixed ladders and similar aids.
  6. Please do not initiate any projects including but not limited to digging, shoring, repairing etc without approval.
  7. Please do not write anything on the walls, including arrows or your name.
  8. Please do not move any artefact around the mine or remove them from the mine.
  9. Please do not interfere with the materials store or take anything from it unless authorised to do so.
  10. Please do not drop litter.
  11. You are welcome to enjoy the Go Below traverses and tyrolean's if you are suitably equipped and experienced to do so. Please do not attempt to use the Goliath zip-line or free-fall as they require specialist training.
  12. Please do not attempt to enter the old Oakeley workings beyond the Cwmorthin boundary (there is a sign in place at the crossing). We do not have rights of access into this mine which is presently being untopped by Welsh Slate. It is dangerous to do so and an incident in here would create extremely serious problems for the FOC.
  13. Cwmorthin, like any disused mine or quarry, is a hazardous environment with numerous dangers including sheer drops, unstable roofs and walls, deep water and loose/slippery surfaces. It is not a show mine and is not suitable for novices or inexperienced persons unless as part of a professionally led group. By entering the mine you signify that your are suitably experienced and equipped to do so, and that you accept full liability for any incident or accident that occurs within the mine regardless of how caused.
  14. You MUST inform a suitable person outside of your intended exit time and stick to it. In the event of your failure to return, that person needs to call 999 and ask for the police, who will muster North Wales Cave Rescue to search for the missing party.

Directions to Cwmorthin

From Blaenau Ffestiniog take the A496 towards Tanygrisiau. When a sign for the power-station appears on the right, turn right into the village. The road leads slightly up hill to a junction. At this junction, go straight-over left up a very steep road leading under the Ffestiniog Railway. Continue climbing, going straight over at a T junction to finally reach a car park high above the village at SH683454.

Park here (note, this car park is notorious for break-ins. Do not leave anything valuable on show!) and follow the obvious rocky track leading up the hill (not the footpath below the waterfall). The track follows the river, continue until you reach the lake (Llyn Cwmorthin). Follow the track around the right hand side of the lake (not left towards Rhosydd) to reach some of the old mine buildings. Keep going around the lake until a big cutting appears on the right, leading into the steep tip-covered hillside. At the end of this cutting is found the adit at approximately SH678463