It's kind of sad that the Blue Hole isn't open for tours anymore. I remember seeing it as a kid with my family, and later on in the 1980's before it closed in 1990. It was just a nice relaxing thing to do on a sunny Sunday.
Here is what the 1940 Ohio Guide said about the Blue Hole:
On State 269 is the BLUE HOLE (adm. 10 cents–15 cents), 2.1 m (L), a beautiful spring, 75 feet in diameter, that daily exudes 7,000,000 gallons of water into the winding race near by. The spring's blue measureless depths reveal iridescent wonders: the simulacrum of an Alpine village, or a mountainside farm, or a medieval castle. The Indians believed the waters were medicinal, and white men marveled at the spring as early as 1761. Visitors have come to it from all parts of the world. When Cold Creek was dammed in 1819, the regurgitant river enlarged the Blue Hole to its present dimensions.
I remember the ubiquitous round signs for the Blue Hole along Route 6. To me, the Blue Hole made Castalia a magical place – along with the Crystal Rock Caves and Deer Park.
Anyway, here are a few postcards to rekindle some Blue Hole memories.
For more information about the Blue Hole, click here for a Wiki entry that also mentions the 'other' Blue Holes in the area. To read some reminisces, you can check out the Roadside America's website or click here for some more interesting recollections on another website.
The best source for information and fantastic photos, however is the Arcadia Publishing book by Glenn C. Kuebeler, Castalia, Cold Creek and the Blue Hole. It's a terrific book and a must-have for your book shelf.