A colossal mine in the United States that has a large green lake inside

In recent years, we've seen quite a few videos of truly amazing underground mining operations here.

The dark underground world that exists beneath the Twin Cities of Minnesota
The ghost tunnels of the old Hill Street subway station in Los Angeles

A week ago, the YouTube channel Action Adventure Twins published a video exploring a colossal mine with abandoned machinery inside. The authors did not indicate the location of this abandoned mine, nor even the country in which it is located, although judging by what we see in the video and from what I have been able to find out, it is in the state of Kentucky, in the United States.

The most striking thing about this enormous mine is that there is a large lake of greenish water inside. That color is not usually a good sign, but despite this, one of the protagonists of the video took a dip in that lake, something that some viewers have criticized in the comments of the video, pointing out that in cases like this it is better to take a test to measure the acidity or alkalinity of the water, in order to avoid unpleasant surprises due to the possible presence of fungi or toxic chemicals:

You can see some screenshots from this video here. Here we see the exterior of this great mine, with two large entrances to its network of galleries.

The interior of the colossal mine. It's not as elegant and stately as Khazad-Dûm, but at least there are no orcs.

A completely rusty old vehicle. My personal vehicle advisors admit they have no idea what model it is. If anyone reading this can provide any information, please post it in the comments.

The green lake inside the mine. I didn't think it was a very good idea to dip my feet in that greenish water, but taking a dip in it (as you can see in the video) should be listed with lots of arrows among the things you shouldn't do in a flooded mine.