There are 23 National Natural Landmarks in Ohio.
| Name | Image | Date | Location | County | Ownership | Description |
|---|---|---|---|---|---|---|
| Arthur B. Williams Memorial Woods | 41.5623°N -81.4268°W | Cuyahoga | municipal | A remarkably pristine remnant beech-maple forest | ||
| Blacklick Woods | 39.9372°N -82.8078°W | Fairfield | county | An outstanding example of relatively undisturbed, old-growth beech-maple and swamp forest communities | ||
| Brown's Lake Bog | 40.6809°N -82.0624°W | Wayne | private | One of the few well-preserved, virgin boreal acid bogs remaining in a region where wetlands have been drained for agricultural use. | ||
| Buzzardroost Rock, Lynx Prairie, The Wilderness | 38.7594°N -83.407°W | Adams | private | Supports many rare or uncommon species and it has an almost 50- year history of scientific observations. | ||
| Cedar Bog | 40.0594°N -83.7956°W | Champaign | state | An excellent example of a marl swamp. Part of Cedar Bog State Nature Preserve. | ||
| Clear Fork Gorge | 40.611°N -82.2868°W | Ashland | state | Clearly illustrates evidence of stream reversal due to the Wisconsin glacier. Located in Mohican State Park. | ||
| Clifton Gorge | 39.7939°N -83.8315°W | Greene | state | Exemplary of interglacial and postglacial canyon-cutting into the dolomites of the Niagara Escarpment. Part of Clifton Gorge State Nature Preserve. | ||
| Crall Woods | 41.0282°N -82.4344°W | Ashland | private | A near-virgin remnant of maple-basswood-beech forest-type. | ||
| Cranberry Bog | 39.9315°N -82.4682°W | Licking | state | The only known bog of its type in existence. Part of Cranberry Bog State Nature Preserve. | ||
| Dysart Woods | 39.9846°N -80.9976°W | Belmont | state | One of the finest remaining examples of the white oak forests of eastern Ohio. Managed by Ohio University. | ||
| Fort Hill State Memorial | Hillsboro39.1131°N -83.4063°W | Highland | state | Excellent outcrops of Silurian, Devonian, and Mississippian sedimentary bedrock and a natural bridge. | ||
| Glacial Grooves State Memorial | 41.6163°N -82.7065°W | Erie | state | Very large limestone glacial grooves. | ||
| Glen Helen Natural Area | 39.8041°N -83.8817°W | Greene | private | Includes a waterfall that carved a large travertine bowl around its pool. | ||
| Goll Woods | 41.5543°N -84.3617°W | Fulton | state | One of the best remaining examples of an oak-hickory dominated forest in Ohio. Part of Goll Woods State Nature Preserve. | ||
| Hazelwood Botanical Preserve | Hamilton | state | Highly detailed study of the site's plant ecology was published in 1929. Managed by the University of Cincinnati. | |||
| Highbanks Natural Area | 40.1439°N -83.0283°W | Delaware, Franklin | county | A forested bluff overlooking the Olentangy River. | ||
| Holden Natural Area | Geauga, Lake | private | A complex of three natural areas. | |||
| Hueston Woods | 39.5725°N -84.7414°W | Butler, Preble | state | A noteworthy example of beech-maple climax forest that has never been cut. Located in Hueston Woods State Park. | ||
| Mantua Swamp | 41.2803°N -81.2114°W | Portage | private | Contains many different wetland communities. | ||
| Mentor Marsh | 41.7292°N -81.3055°W | Lake | state | Consists of marsh vegetation, aquatic plants, swamp and bottomland forest, and upland forest. Part of Mentor Marsh State Nature Preserve. | ||
| Serpent Mound Cryptoexplosive Structure | 39.0333°N -83.4°W | Adams, Highland, Pike | private | A structure of undetermined origin exposed by differential erosion. | ||
| Tinker's Creek Gorge | 41.365°N -81.6097°W | Cuyahoga | municipal | Contains a virgin oak-hickory and virgin beech-maple-hemlock forest. | ||
| White Pine Bog Forest | Geauga | municipal, private | The only remaining near-virgin remnant white pine boreal bog in Ohio. | |||