The Berkeley Pit is an old open pit copper mine in Butte, Montana. It currently serves as a tourist attraction with a $2 admission fee to access the viewing platform.

The Berkeley Pit traces its history back to 1955 when it was opened and operated by Anaconda Copper. It is quite an interesting site, as it presents a good example of an open-pit mine in the city, which has always been a big mining town. It was closed down in 1982.

Today, the Berkeley Pit poses a serious environmental problem due to the groundwater that is filling the pit slowly. The water, mixed with oxygen, tends to release acid and pollute the Silver Bow Creek or the headwaters of the Clark Fork River. Authorities are taking actions to prevent such things from getting worse, however.