It is an entrenched stream whose meanders have cut deep into the Mississippian limestone bedrock. The limestone walls along the river are usually shrouded in a heavy cover of trees and shrubs. Rock is a constant feature of the stream bed, but much of it is covered by sediment. The rapids reveal gravel bars, however, and the canoeists must remain alert for submerged boulders which can be quite hazardous. The width, depth, and gradient of the river vary, but it is about 85 feet wide.
Average depth is about five feet deep, and the river falls at about four feet per mile.
The Blue River area was first explored by Squire Boone, Daniel Boone's brother. He found large Indian populations whose sites can still be found today. Fredericksburg to Milltown Above Fredericksburg, the river generally lacks the necessary flow for canoeing. In Fredericksburg, an access site and parking area are also available to use for a fee downstream of the bridge on the right bank. This is a rather strenuous 24-mile float.