2 observations in 1 expeditions
Another example of a North Wales slate mine with flooded lower workings. The pumps were finally switched off here in 1999 allowing water to rise slowly over the next decade or so. It now appears to have reached a stable level as gauged against the steps of a "manway". The floors here are around 70ft apart with at least 2 levels below water. Although this mine was worked as late as the 1990s, earlier sections had long been abandoned, often with ancient artifacts left in place. These may take the form of miners' personal effects such as clay pipes, lamps and tools or mining infrastructure like rail lines, trucks and bridges. An openROV would allow us to get beyond the tantalising glimpses we're currently afforded of this lost world. But time is of the essence. Modern day untopping work is threatening access to this particular mine with some unique sections already lost.
In North East Wales, a substantial, underground lake was discovered by miners in 1931. Flooded to hundreds of feet below sea-level, its true depth has long been the subject of speculation. Several thousand gallons of water a minute run through, draining to sea along miles of man-made tunnel. This crystal clear water provides excellent visibility but diving is precluded by the long and arduous access route. Exploration by ROV appears the obvious solution and would provide an invaluable insight into this fascinating natural cave system.