The land of Harriman State Park holds important iron resources. During the 19th century the iron ore held in the Harriman State Park area was mined extensively. Much of the Ore removed was taken to Clove Furnace, which is visible from I87, to be turned into pig iron. The resulting pig iron was taken to area foundries where it was transformed into cast iron objects. Much of the Harriman State Park ore was transported to West Point Foundry in Cold Spring where it was used to create cannons and other munitions in the Civil War. You can read more about this here. Today, most of the mines have been been completely collapsed, flooded or closed off making them impossible to enter. However, there are a few that remain intact. Of these remaining mines one of the coolest is the cavernous Bradley Mine.
The Bradley mine sits relatively close to the Appalachian Trail and is great photographic subject matter because of its well defined entrance light source. I took a stroll into the mine with my DSLR and a tripod recently to try and capture its essence.
Bradley mine is very dark inside so visitors that want to see it first hand should come prepared with headlamps. Proper caving gear also includes a helmet, overalls and waterproof boots. Bradley Mine is partially flooded so be prepared to get wet if you want to do a full exploration of it.