When I was up in Potter county Pennsylvania last week, I went to see the Couldersport ice mine. It’s a deep hole nestled in a hemlock forest and every summer ice forms in the “mine”. It melts away during the fall/winter seasons and starts forming again in the spring when the weather starts to warm. They’ve had the Discovery channel out there a little while ago. No one can figure out why it does this….there are some theories but no one knows for sure. It’s the only one like it in the world.