The forest is nearby the city of Onamia and is along the Rum River, just downstream (south) of Mille Lacs Lake.

The forest is home to many Northern hardwoods such as maple, oak, ash, elm and basswood that occupy most of the upland areas while tamarack and black spruce are found in lowland and marshy areas.

In 1935, the Minnesota Legislature established both the Rum River and Mille Lacs State Forest.

[3] Popular outdoor recreational activities in the forest include dispersed camping.

Along the northern boundary of the forest is Mille Lacs Kathio State Park which contains 19 identified archaeological sites, making it one of the most significant archaeological collections in Minnesota.