Carnglaze Caverns Review: Is Cornwall’s Underground Slate Mine Worth Visiting?

Carnglaze Caverns is one of Cornwall’s more unusual days out: an old underground slate mine near St Neot, just off the A38 between Liskeard and Bodmin, with three caverns, a blue-green underground lake and a woodland walk through ancient oak trees.

I like Carnglaze, but I wouldn’t oversell it. This is not a huge, all-day attraction. It is a compact, atmospheric place that works best when you want something different from the beach, something useful for a wet-weather day, or something to pair with a wider Bodmin Moor or South East Cornwall outing.

My honest verdict: Carnglaze Caverns is worth visiting if you go for the atmosphere, the underground lake and the woodland setting. Treat it as a memorable half-day stop rather than a major full-day attraction, and it makes much more sense.

Carnglaze doesn’t need to be enormous to be worth your time; it just needs to be honest, atmospheric and a bit different.

Carnglaze Caverns at a glance

Best for: families, rainy days, curious adults, Bodmin Moor day trips, and visitors staying near Liskeard, Looe, Polperro, Lostwithiel or Bodmin
Main draw: Cornwall’s underground slate mine and flooded underground lake
Time needed: around one and a half to two hours for the caverns and woodland at an easy pace
Cavern temperature: around 10°C all year, so take a layer
Footwear: wear sensible shoes with grip
Dogs: welcome outdoors on leads, but not underground except registered trained assistance dogs
Parking: free on-site parking, with low-mobility spaces and overflow parking at busy times
Good to know: numbers underground are limited, so a timed booking is the safest plan in busy periods

What is Carnglaze Caverns?

Carnglaze Caverns is Cornwall’s only underground slate mine open to visitors. The site began as an open quarry before miners started digging underground by hand more than 300 years ago. That work created three large caverns inside the hillside, and those caverns now form the main visitor route.

You head about 150 metres into the hillside and around 60 metres below ground. The first cavern sits on the upper level, then a flight of around 50 steps takes you down to the lower caverns. The third cavern is flooded, creating the underground lake that gives Carnglaze its most memorable moment.

Before going underground, you’re given a helmet and the basic safety information. Once inside, the visit is self-guided, with information boards telling the story of the mine and the people who worked there.

What I like is that Carnglaze still feels like a real place. It hasn’t been turned into a noisy artificial experience. The slate walls, the cool air, the old mine workings and the still water do the heavy lifting.

What are the caverns like?

The caverns are cool, quiet and atmospheric rather than vast and dramatic at every turn. That matters for expectations. If you arrive imagining miles of underground tunnels, you may find it smaller than expected. If you arrive expecting a short but distinctive underground visit, it lands well.

The route gives you a sense of Cornwall’s slate-mining past without becoming dry or museum-heavy. There is also a mineral collection in the first cavern, with material connected to mining and quarrying across the South West.

Cornwall is often talked about through tin, copper, fishing and beaches, but Carnglaze gives you a different angle. The dark blue slate from this area was part of the working landscape too, especially around South East Cornwall.

The underground lake is the highlight

The underground lake is the best part of Carnglaze Caverns. After the steps, the slate and the darker spaces, the blue-green water has a lovely stillness to it. It feels quietly theatrical, but not forced.

This is the bit I’d slow down for. Let your eyes adjust, listen to the sound of the cavern and give yourself a moment before moving on. It feels very unlike the Cornwall most visitors picture. No harbour, no beach, no clifftop view — just slate, water and that strange calm you only get underground.

It is also the reason Carnglaze works well as a rainy-day attraction. You are not just hiding from the weather; you are seeing a completely different side of Cornwall.

How long does Carnglaze Caverns take?

The underground caverns usually take around 25 to 30 minutes if you read the boards and don’t rush. The woodland walk adds around 20 minutes, although it can take longer with children or if you stop for the views, carvings and little details along the way.

For the full visit, I’d allow one and a half to two hours. That gives you time to do the caverns properly, walk through the woodland, have a drink or snack, and avoid turning the whole thing into a quick in-and-out.

If you are planning a day around it, I’d pair Carnglaze with somewhere nearby rather than making it the only stop.

Is Carnglaze Caverns good for children?

Yes, Carnglaze Caverns is good for children, especially if they like caves, helmets, woodland trails and anything that feels a bit adventurous. It is also short enough for families who don’t want a long, expensive, high-effort day out.

The children’s appeal is simple:

• The helmets make it feel like a proper adventure
• The underground lake gives the visit a clear “wow” moment
• The woodland walk has faeries, dragons, mushrooms and carvings to spot
• The route is manageable rather than exhausting

There are a few sensible cautions. This is a retired slate mine, not a soft play centre. Keep children close underground, take care on the steps, and don’t let anyone climb on loose slate. Very young children may also find the helmets a bit large.

The woodland walk at Carnglaze

The woodland walk is more than a spare bit of greenery after the caverns. Carnglaze sits in around eight acres of ancient oak woodland, and the route through Quarry Wood gives the visit a softer, fresher second half.

The path winds through the wooded hillside, with seasonal streams, woodland flowers, a view towards St Neot village and a scattering of faeries, mythical creatures, mushrooms, dragons and wood carvings. It gives children something to hunt for without making the place feel overdone.

In spring, the bluebells can be especially lovely, usually around late April into mid-May depending on the weather. Like most seasonal things in Cornwall, they don’t follow a perfect calendar, but if you catch them well, they add a lot.

Wear proper shoes. The woodland is steep and uneven in places, and it feels like real Cornish woodland rather than a flat garden trail.

What to wear for Carnglaze Caverns

The caverns stay around 10°C all year. In summer, that can feel wonderfully cool. On a grey day, it can feel properly chilly if you turn up in thin clothes.

I’d wear:

• A jumper or light jacket
• Trainers or walking shoes with grip
• Clothes you don’t mind getting a little dusty or earthy
• An extra layer for children

I wouldn’t visit in flimsy sandals if you want to enjoy the caverns and woodland properly.

Food, drink and facilities

You can bring a picnic to enjoy in the grounds, but food and drink should stay above ground. Own food should not be eaten in the café area, and because Carnglaze is a licensed site, you should not bring your own alcohol.

There is usually a small café-style refreshment option on site, along with toilets and visitor facilities. I’d still treat this as a simple, rural attraction rather than somewhere to rely on for a full meal.

For a relaxed visit, I’d bring water, dress sensibly and plan food either as a picnic or as part of your wider day nearby.

Dogs at Carnglaze Caverns

Dogs on leads are welcome in the outdoor areas, including the grounds and woodland, but dogs are not allowed underground, except for registered trained assistance dogs.

That makes Carnglaze workable for dog owners if someone is happy to stay above ground or if you are mainly using the woodland and outdoor areas. On warm days, be sensible. There are shaded parking spaces, but cars and dogs are still a bad mix in summer.

Accessibility at Carnglaze Caverns

Accessibility at Carnglaze is mixed, which is understandable for an old mine site in a wooded valley.

The upper cavern, The Rum Store, is accessible, including for wheelchair users. The lower cavern has more limited access via a ramp to a viewing platform, but the underground lake and lower levels involve an old flight of steps with handrails.

The terraced gardens are partly accessible for a shorter stroll, with places to sit. The woodland walk is steeper, rougher and not fully accessible.

My honest advice: if access is a major factor, treat Carnglaze as a place where some parts are manageable and others are naturally restricted by the historic site.

Booking, tickets and opening times

Carnglaze usually works with timed visits, and booking a slot ahead is the safest plan, especially in school holidays, bad-weather spells and busy visitor periods. Numbers underground are limited, so arriving without a booking can mean waiting or missing your preferred time.

Opening patterns vary by season. Normal opening is typically Wednesday to Sunday, plus bank holidays, with broader opening during holiday periods. Last entry is before closing, and private events can occasionally affect visitor access.

Ticket options usually cover the caverns, gardens and woods, with categories for adults, concessions, children, under-threes and families. There may also be a gardens-and-woods-only option for anyone who doesn’t want to go underground.

I wouldn’t build the article around fixed prices, because they can change. The practical point is this: choose the right ticket type, book a sensible time slot, and don’t leave it until the car park.

Where is Carnglaze Caverns?

Carnglaze Caverns is near St Neot, close to Liskeard, on the southern edge of Bodmin Moor.

Address:
Carnglaze Caverns, St Neot, Liskeard, Cornwall, PL14 6HQ

Driving is the easiest way to get there. It sits just off the A38, with brown tourist signs from the Liskeard direction.

Public transport is possible, but it needs more planning. Liskeard and Bodmin Parkway are the nearest mainline railway stations, and rural bus services can be limited, especially on Sundays, bank holidays and evenings. If you are travelling without a car, sort the journey properly before committing to the day.

What to do near Carnglaze Caverns

Carnglaze works best as part of a wider South East Cornwall or Bodmin Moor day. I wouldn’t overpack the itinerary, but these pairings make sense:

• St Neot — a quiet village stop nearby
• Golitha Falls — a woodland and river walk, good if you want more fresh air
• Liskeard — useful for a practical town stop
• Bodmin Moor — best on a clear day when you want bigger landscapes
• Looe or Polperro — good if you are heading back towards the coast
• Lostwithiel — a nice option if you want independent shops, antiques and a slower town wander

If the weather is awkward, I’d do Carnglaze first, then keep the second stop flexible.

Is Carnglaze Caverns worth visiting?

I’d recommend Carnglaze Caverns if it suits the kind of visit you want.

It is worth visiting, but it is worth visiting for the right reasons. It is not one of Cornwall’s big glossy attractions, and that is not a weakness. Its appeal is smaller, cooler and more grounded.

Go for the underground lake, the old slate caverns, the woodland walk and the chance to see a less obvious side of Cornwall. Go when the beach feels too busy, when the weather looks unreliable, or when you want something that feels rooted in the landscape rather than manufactured for visitors.

It is especially worth considering if you are already staying near Liskeard, Looe, Polperro, Bodmin, Lostwithiel or Bodmin Moor. If you are coming from the far west of Cornwall, fold it into a bigger day rather than making a long drive for the caverns alone.

Carnglaze is a good place: practical, atmospheric, quietly memorable and just unusual enough to stick with you afterwards.

FAQs about Carnglaze Caverns

How long do you need at Carnglaze Caverns?

Allow around one and a half to two hours for a comfortable visit. The caverns usually take about 25 to 30 minutes, and the woodland walk adds around 20 minutes or more depending on your pace.

Is Carnglaze Caverns good on a rainy day?

Yes. Carnglaze is one of the better rainy-day attractions in this part of Cornwall because the main cavern visit is underground. The woodland can still be enjoyable in light rain if you have decent shoes and coats, but it will feel more rugged in wet weather.

Is Carnglaze Caverns suitable for young children?

Yes, but adults need to supervise properly. There are steps, uneven surfaces and loose slate underground, so it is not a place to let children run ahead. For many families, the short route, helmets, lake and woodland trail make it a strong option.

Can dogs go into Carnglaze Caverns?

Dogs on leads are welcome outdoors, but not inside the caverns, except registered trained assistance dogs. If you are visiting with a dog, plan around the woodland and outdoor areas, or make sure someone in your group is happy to stay above ground.

Do you need to book Carnglaze Caverns in advance?

Booking ahead is the sensible choice, especially during school holidays, wet-weather days and busy visitor periods. Numbers underground are limited, and timed visits make the day smoother.

Is Carnglaze Caverns accessible?

Parts of Carnglaze are accessible, but not all of it. The upper cavern is accessible, while the lower caverns and underground lake involve steps. The gardens have some accessible areas, but the woodland walk is steeper and uneven.

What should I wear to Carnglaze Caverns?

Wear a jumper or light jacket and sensible shoes. The caverns stay around 10°C all year, and the woodland path can be steep or muddy depending on the weather.

Is there parking at Carnglaze Caverns?

Yes, there is free on-site parking, including low-mobility spaces. At busier times and events, overflow parking may be used, with a short woodland walk back to the caverns.

What is there to do near Carnglaze Caverns?

Nearby options include St Neot, Golitha Falls, Liskeard, Bodmin Moor, Lostwithiel, Looe and Polperro. I’d pair Carnglaze with one nearby stop rather than trying to turn it into a packed itinerary.