The Big River State Forest is a state natural reserve and recreational area locate in Keithsburg, Illinois. It is part of the Illinois State Parks system and is used as a forestry education are by the Illinois Department of Natural Resources.

The park is located about 8 miles north of Oquawka on the Oquawka-Keithsburg blacktop and is well signed and accessible from the road. The state department of natural resources uses the Big River State Forest to demonstrate sound forestry practices and holds educational activities and demonstrations to interested groups in the park.

There are several recreational opportunities in the state forest. There are several picnic area in the park complete with shelter houses, camp stoves, tables, and drinking water. Tent and trailer sites are also available for campers.