Dont call it cave-diving - mine-diving is quite different, says Martyn Farr, not least because of the industrial remains you get to see down there. But if you plan to delve into Britain's abandoned pits, you need to know what you're doing

HAD NEVER DIVED IN ANYTHING QUITE LIKE THIS, and all my senses were at red alert. There were plenty of belay points for my guideline, but the environment and the consuming blackness were almost beyond belief.
No one had ever dived this place; until it had been assessed, it required the ultimate caution.
Immediately ahead was a sudden drop-off. I floated gently downwards, trailing the all-important line carefully behind me. As I passed the 25m mark, a fantastic sight loomed into view. In this world of black and grey, a form had suddenly taken shape.
It was a tram, or rather a train of three small trucks, lined up where they had been parked many, many years ago.
This was the most unusual thing I had come across in a flooded mine; like wreck diving, it was eerie and distinctly spooky. These subterranean corridors speak volumes from a bygone age.
I am always looking for new and interesting places to dive, and mines certainly fall into this category. Mines and caves are often synonymous to the open-water diver but in fact they are quite different.
Complex and extensive mines can be found throughout the UK, and indeed all over the world. The mine to which I referred earlier was the Cambrian Slate Mine, with its miles of tunnels, both above and below water.
It is situated near Llangollen in Wales, a rural backwater and a place that gives the casual visitor little indication of its industrial past, and certainly no clue as to its important mining heritage.
Finding a mine that is suitable for diving is frequently difficult. Access may be prohibitive with bulky equipment, or the site may simply be too dangerous. But Britain is blessed in that a tremendous variety of minerals have been extracted over the historical period, and there are some amazing sites to see and experience.
Just below the water surface in the slate mine, a spectacular stone stairway led down into the depths, with dry stone walls set to either side. The roof overhead was massive slab at a 45 angle, cleaved seemingly as smooth as the huge blocks of slate so painstakingly won in the days of the Industrial Revolution.
This was a weird place invested with so much history, every surface caked in a crumble of granular debris or fine silty dust. Air raced up the roof slabs like a turbulent freshwater stream defying gravity, a literal stream of clear and white reflective bubbles.
Occasionally shards of rock, some quite sizeable, were dislodged, carving a distinct zig-zag path through the water as they glided gracefully to the floor.
I could just imagine scores of miners puffing and panting back up this staircase after a long, arduous day toiling in the darkness, wearily trudging back to the surface for the long walk home.
This corridor had tales to tell, and no one had dived here since the place was finally abandoned and quietly filled with water, perhaps 60 years earlier.
Re-discovering a place like this would fire anyones imagination. The trams lie on rails winding off into the distance at 27m depth. To my left was a flimsy cabin-type structure that had housed a now-broken boiler.
All along the level, all manner of mine artefacts and features were revealed. There were tally marks, indicating the number of trams that had passed, and clusters of miners initials chalked on the walls. There were pipes and chains hanging from walls and ceilings high overhead; this was a very different mine to the iron and stone workings we normally visit. This was wreck-diving without the sea!
In 2006, we eventually managed to connect the majority of the surface pools in the slate mine to the level at 27m, but clearly there are many passageways still to explore.
Before readers eagerly start thinking about a mine-diving trip, a number of points must be considered.
Firstly, one must develop a healthy understanding of the environment.
Many old workings such as coal-mines are inherently dangerous and should be avoided.
Mines were excavated to make money, and the primary concern was the extraction of some valuable commodity by the cheapest means possible. Various extraction methods such as explosives clearly fractured and disturbed surrounding rocks. In time natural processes of settlement and the sheer weight of rock above caused the tunnel to weaken, destabilise and perhaps collapse.
If the original tunnel was supported by artificial timber or stone supports, there should be real concern for roof stability.
Just as bubbles exhausted inside a wreck can lead to collapse of the structure, so too will bubbles gather in cracks in the roof of the mine, with the same end result.
In many mines, roof and wall supports frequently hold back, or conceal, large quantities of loose rock debris.
So each mine, and indeed each section of each mine, must be individually and carefully evaluated. Here local knowledge is very important.
The very air in abandoned mines is frequently unhealthy. It may be depleted of oxygen and, while seemingly breathable, may not be capable of sustaining life.
Again, there may be an excessive, dangerous accumulation of carbon dioxide, or even of other, more lethal gases. These may be of the explosive variety, such as methane, or perhaps originate from pollution. Pollution of the water itself may be a concern.
Mines also contain certain fixtures, such as old telephone or electrical wiring, rusty pipework and other items, frequently left suspended from long bolts driven into the roof and walls. Discoloured and rusty, such fixtures may appear almost invisible, and constitute a hazard in their own right. Remember, too, that wire cannot be cut with a knife!
Rarely is there any discernible flow in a flooded mine. However, during periods of heavy rainfall, quantities of fine silt will invariably be carried underground. This may result in cloudy water for a period until the sediment settles to the floor. Because the silt is very fine, it is easily disturbed and will rise with the least provocation.
Rarely do mines consist of a single tunnel; more often they are complex, and maze-like. To lose visibility and orientation in this type of environment could be fatal.
So treat mines with extreme respect. They present convenient access, but remember that rock stability, air and water quality and abandoned equipment all represent potential hazards.
Easy all-year access, spacious tunnels and clear water may seem an attractive proposition, but the comparison with wreck-diving is impossible to ignore. To the aspiring overhead-environment diver, mine exploration presents an inviting challenge. Here are some possibilities:

Hodge Close Slate Mine
Hodge Close, near Coniston in the Lake District, is a fascinating site at any time of year. It consists of a flooded slate quarry and a couple of sporting passageways.
The main tunnel, a little over 2m square, is accessed at 25m depth. It opens to several chambers along its length and presents a good sporting dive at times when most other diving would be blown or washed out. The water is generally cold at this depth - 6C or below.
Visitors would be prudent to consider their level of training before embarking on any penetration dive here. Three inexperienced divers have died here in past years.

Dinas Silica Mines
These old stone mines at the head of the Neath Valley, in South Wales, lie on land owned by the Forestry Commission, which posts Danger signs to deter casual and inexperienced visitors from entering. You take a 600m walk to reach the entrance, followed by a further short walk underground to reach the water.
Water clarity here is stunning; visibility is frequently in excess of 30m, unless a previous group has stirred up sediment. This place is a veritable labyrinth of underwater tunnels with one old tram, leading to a maximum depth of 23m.

Iron Mines, Forest of Dean
Iron mines often present a relatively stable environment and generate excellent prospects for underwater activity. There are scores of old, abandoned examples in the Forest of Dean, and many terminate at water, but the difficulty of transporting equipment to most of these sites is the reason they are rarely visited.
However, near Coleford lies the Noxon Park complex. These mines again lie on Forestry Commission land, but despite the Danger signs, traditionally there has been no difficulty with access.
A formal access arrangement exists here; seek appropriate advice.
There are five or six dive sites, the nearest of which lies about 400m from the road. A reconnaissance to assess conditions is advisable. Depending on the season, water levels can vary by as much as 15m in the complex as a whole, and visibility can exceed 30m.
While the water is a refreshing 9C, be warned: the red clays and muds through which you travel to gain the dive site may be impossible to remove from your kit!

Holme Bank Chert Mine
Holme Bank Chert Mine is located in a quarry on the outskirts of Bakewell in Derbyshire. The entrance is gated and locked, and permission will be given only to appropriately qualified dive leaders, normally of the Cave Diving Group of Great Britain. The underwater sections
of this stone mine are straightforward, consisting of a shallow tunnel leading to two points where divers can leave the water and make their way back to the entrance by dry, walking galleries.
Visibility is normally crystal clear for the first dive, but given the restricted size of the underwater passages, sediment may be quickly disturbed.
There are no major attractions at this site, but it does give an excellent insight to underground workings.

Dive line found at any of the above sites should be treated as suspect.
The most important aspect of mine-diving is training and environmental awareness. No verbal communication, text or video will ever replace a structured course delivered by a professional in this field. There is no formal mine-diving qualification, and the closest you will
get is cave-diving certification.
Given that all mines are on private land, and that land-owners are becoming increasingly touchy about their legal liabilities in granting entry, this is generally the only qualification that
will be recognised - if they are prepared to allow entry at all.
To ignore the wishes of the owner or any locally negotiated access agreements is to risk closure of the site to all.
If in any doubt about your knowledge of the environment, or your competence to undertake a mine dive, please stay out! You are not only risking your own life but almost certainly jeopardising long-term access to what may be a unique recreational resource.

Divernet Divernet
Tunnel in Hodge Close slate mine
approaching the mine
and the Forest Pillar chamber
Old rolling stock in the Dinas Silica Mine.
Entrance to the Cambrian slate mine, near Llangollen.