Shuniah mine was in operation in the mid 19th century as a silver mine. The mine never really profitable, but helped lay the groundwork for the more famous Silver Islet mine. It was shut down in the early 1870s.
Recently the fill they used to close the mine has begun sinking, and as a result the entrance of the main shaft is visible for around 30 feet. Along with the main shaft, numerous ventilation shafts have begun reappearing as well. The city of Thunder Bay has a plan to, over the next few years, re-fill the mines and to build a fence around the area. Until they do that, the shafts are completely visible and accessible via the shuniah mines bike trails. See it now before it's gone!