It's so pretty from the outside that you may not realize what you are getting into. Everyone should visit this amazing Iowa attraction at least once. Entering the cave is entirely optional.

The Spook Cave boat tour is a 40-minute guided trip through a flooded cave. If you are at all claustrophobic, you may want to just enjoy the beautiful park instead of descending below the earth's surface for the better part of an hour.

The cave was discovered in 1953. It had been the subject of many rumors over the years. There was only a small hole where the entrance is, now.

Residents of the long-gone town of Beulah referred to the spring hole (now the cave's entrance) as Spook Hole.

They heard a constant stream of strange noises, chatter, voices, and echos coming from the hole in Bloody Run Hollow. Assuming they were sounds of the tormented trapped spirits of early settlers, most stayed away.

Beulah Falls remains mostly unchanged.

The hole at the top of the falls resembles the original entrance to Spook Cave before its founder decided to turn it into a tourist attraction in the 1950s.

For those that don't mind boats, confined spaces, dark clammy caves, and a one-way 40-minute tour of a space that's been haunted for hundreds of years, Spook Cave is a must-do.

Your enjoyment of the tour depends entirely on your ability to tolerate certain things that some people find impossible. Many children take this boat tour and have the time of their lives. Some adults hyperventilate before the cave entrance disappears from view and have to just put their heads down and wait for the end.

The tour guides are excellent.

They are experts when it comes to local lore and legend. They know a lot about the rock formations and history of the area, as well.

Gerald Mielke is the man who, in 1953, dynamited the entrance to the cave so it would be large enough to accommodate tourists.

He established the park as a campground and made it a regional attraction.

The driftless area of Iowa and Wisconsin has many caves, sinkholes, and underground wonders.

For the curious and brave, this is one you can see up close. You'll see manganese and calcite formations in the half-mile tube of rock.

Here's a warning: in some places, the cave is so small you'll need to duck to get through.

Once you emerge from the other side, you can take a deep breath and enjoy the kitschy Spook Cave store.

Have a cold Coke; you earned it.

Remember: there's no shame in simply waiting for the rest of your party to finish the tour from the safe side the cave entrance.

Have you been to Spook Cave? Did you go inside? Are you OK?