User blog comment:Sporekypig/Weird buildings theories?/@comment-73.179.194.38-20161205042351

I was trying to find max depth in the small submersible. Anyway I found a deep hole, went down 5000 meters and realized it had opened up into a huge underwater cavern that was literally bottomless. I tried going back up and hit the roof of the cavern. after exploring for a while I realized I was not finding the way back out, so I decided to abandon the sub and tunnel to the surface using the terraformer. After a long time I broke into a cavern above the huge one. There were warpers in there and a large BUILDING, lit with green light, did  not look man made. I swam around it and tried to find a way in but couldnt, then i tunneled the rest of the way to the surface. Its a lost underground city. I am sorry I am neww to the game so didnt have coordinates, but its there.