Located within Blackstone Valley, the reservation is managed by the Massachusetts Department of Conservation and Recreation.

Previously owned by the Whitin Machine Works, Purgatory Chasm was declared a state park in 1919.

[1] The reservation is notable for its .25-mile-long (400 m), 70-foot-deep (21 m) chasm in granite bedrock with abrupt precipices and caves.

According to one source, it was created when glacial meltwater ripped out bedrock at the end of the last Ice Age.

There are 2 miles (3.2 km) of hiking trails, and rock climbing is allowed by permit.