I hiked in each of the 200 counties within 3 hours (210 miles) of Indianapolis during 2020-21. These 10 locations were not in the top 30, but they deserve “honorable mention” and are surely worth a visit.
Near the Indiana/Illinois border, SE of Kankakee is a sand based savannah with unique vegetation.

https://www2.illinois.gov/dnr/INPC/Pages/Area3IroquoisHooperBranchSavanna.aspx
Far south within the Hoosier National Forest is a nature preserve with a challenging hike up a stream valley, stream bed ending at two small waterfalls from the cliffs of this valley.

https://www.crawfordcountyindiana.com/attractions/park-scenic/yellow-birch-ravine/
Near the Indiana/Michigan border, part of the South Bend parks system is a kettle lake of true beauty. There is a boardwalk into the lake and other trails in the glaciated area.

http://www.sjcparks.org/591/Spicer-Lake
The Hoosier National Forest has dozens of strong hiking options. The Pioneer Mothers Memorial is located just outside of Paoli, IN (yes, Paoli Peaks skiing area). Stunning old growth forest. Easy 1 mile out and 1 mile back trail.

https://www.fs.usda.gov/recarea/hoosier/recarea/?recid=41586
Fall Creek Gorge is a nature preserve hike down a stony creek north of Covington, IN near the Illinois border. It is now closed.

https://www.nature.org/en-us/get-involved/how-to-help/places-we-protect/fall-creek-gorge/
Nearby Williamsport Falls is a worthy substitute.

https://en.wikipedia.org/wiki/Williamsport_Falls
Boone County Arboretum is a very well laid out facility 20 miles south of the Cincinnati airport.

Devou Park is a community park in Covington, KY with amazing views of the Ohio River valley and Cincinnati.

https://www.exploredevoupark.org/?gclid=EAIaIQobChMI8rCOtIGN9AIVlmxvBB2vBQ1DEAAYASAAEgLCcvD_BwE
Yew Dell Botanical Gardens is another Kentucky arboretum, east of Louisville.
Cedar Line Nature Preserve is just 30 south/southeast of Cincinnati, but it is “worlds away”. The drive through steeply ravined hills near the Ohio River is as enjoyable as the remote feeling hike.

https://pendletoncounty.ky.gov/Pages/CedarLineNaturePreserve.aspx
Springfield, OH, midway between Dayton and Columbus, OH is noted for Wittenberg University, childhood home of John Legend and … Gallagher Fen State Nature Preserve. A fen is a special type of wetland.

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