Ohio is home to some pretty impressive geological wonders, both manmade and natural. Many of the Buckeye State's natural wonders are actually unique to the rest of the world - meaning you won't find anything else like them on Earth. We've compiled a list of what we believe to be the most impressive Ohio natural wonders and mapped them out in a road trip loop for you.

Grab a friend or two, start at the natural wonder nearest you, and work your way to the others. And use this Google Map of the trip to guide you along the way.

1. Glacial Grooves Geological Preserve

Although you'll have to take a ferry to this first natural wonder, it's absolutely worth it. Few people are aware that Kelleys Island is home to the largest accessible glacial grooves in the world. The Glacial Grooves Memorial measures 400 feet long and 35 feet wide. This is one of the most remarkable of the Ohio natural wonders.

2. Seneca Caverns

Located in Bellevue, Ohio is another geographical wonder that was first discovered in 1872. When you venture to these caverns you will travel through "The Earth Crack" and view the Ole' Mist'ry River. It's one of the most beautiful places in Ohio.

3. Brandywine Falls

Cuyahoga Valley National Park in northeast Ohio is home to a breathtaking 65-foot waterfall that flows from Brandywine Creek. Known as Brandywine Falls, these easily accessible, beautiful falls are a popular highlight within the park. Wooden pathways and stairs lead the way to Brandywine Falls - which you can hear before you see. Softer layers of rock below the falls include Bedford and Cleveland shales, which were formed from mud found on the sea floor that covered the area 350-400 million years ago. This is one of the most gorgeous waterfalls in Ohio.

4. Rockbridge State Nature Preserve

The Rockbridge State Nature Preserve in the small town of Rockbridge features a natural bridge that stretches more than 100 ft. long -- and it’s truly incredible. (After steady rainfall, the water trickling down into the ravine increases and forms what locals call "Rockbridge Falls" beneath the bridge.) It's one of the most awe-inspiring natural wonders in Ohio.

5. Old Man's Cave

Hocking Hills State Park is arguably Ohio's most beloved state park, where waterfalls, caves, unique rock formations, and hiking trails abound. Old Man's Cave has an interesting history and origin to its name. Legend has it, a 19th-century hermit who once lived in the cave, (named Richard Rowe,) is buried under a cave ledge in the area.

6. The Rock House

Within the Hocking Hills State Park area in Logan is the beloved Rock House, where visitors can freely explore this unique cave with a 25-foot-high ceiling and window-like openings. Evidence shows that the homey Rock House was often used for shelter by past visitors, Native Americans, and even bootleggers, robbers, and horse thieves.

7. Glen Helen Nature Preserve "Yellow Spring"

Within the town of Yellow Springs, you'll find the official "Yellow Spring" (which actually looks more orange than yellow) at the Glen Helen Nature Preserve. The nature preserve covers 1,000 acres and features a 25-mile network of footpaths that allows visitors to observe 400-year-old trees, limestone cliffs with waterfalls and overhangs, and the official yellow spring.

8. Crystal King and the Ohio Caverns

Within the Ohio Caverns is one of the world's largest and most perfectly formed stalactites. Crystal King is nearly five feet long, weighing an estimated 400 pounds, and is estimated to be more than 200,000 years old. This is perhaps the most amazing of the Ohio natural wonders.

9. Oak Openings

Close to Toledo, you'll find what's considered to be Ohio's rarest ecosystem (and one of the world's rarest ecosystems) where rare plants and animals, oak forests, sand dunes, savannas, tall-grass prairies, and swamp forests all thrive in harmony. This is one of the most remarkable places in Ohio.

What do you think of this list of the best of the Ohio natural wonders? Are you up for this road trip? Let us know in the comments!

For even more places to explore in Ohio, check out our previous article; Everyone Should Explore These 13 Incredible Places In Ohio At Least Once.