BLACK HAWK, S.D. (KELO) — About a dozen houses in Black Hawk, South Dakota sit empty, after a sinkhole, connected to an old mine, forced families to evacuate. The problems started last Monday when the ground started to give way. While its left a lot of uncertainty for people who call the neighborhood home, the situation has lead to a unique discovery.

Adam Weaver, Nick Anderson, and David Springhetti are cave explorers with Paha Sapa Grotto. When they decided to take a look inside the Black Hawk sinkhole, they had no idea what was in store for them.

“When we actually dropped down into it, I did not expect what we found was pretty exciting. First, we thought it was a cave because we saw this big room but then immediately saw the debris, the pillars and we were like, ‘Okay this is mine,'” Nick Anderson, Paha Sapa Grotto caver, said.

“The first thing that struck me is that this is quite unstable in terms of the ceiling, there’s like big rocks that are laying down this way but should be flat on the ceiling,” David Springhetti, Paha Sapa Grotto caver, said.

Since the sinkhole appeared on Monday, crews have learned that the mine is 650 feet long end to end and about 60 to 150 feet wide.

“It’s kind of an eerie place for us because we are cave explorers, not mine folks. So it’s weird seeing timbers in there and cars and trash and a cave, you usually do not have those things,” Adam Weaver, Vice Chairman of the Paha Sapa Grotto, said.

Crews have learned that the hideaway mine is made out of gypsum, which is very pretty to look at, but dangerous to have a neighborhood built on top of.

“This was a chance to come and help these people who I feel terrible for because it’s just like their lives have been upended,” Springhetti said.

While gypsum mines can be hidden in different areas in the Black Hills, not all of them are located under communities.

The Black Hawk Volunteer Fire Department wants to remind people that they are not allowed in or around the sinkhole.

Photo courtesy Dan Austin.