A couple spent $300,000 building a hidden underground home that you can enter by going down a 12-foot spiral slide tucked inside an unassuming tent

The Parrishes launched their company, Treehouses of Serenity, which builds unique travel destinations along the Blue Ridge Mountains in Asheville, North Carolina, in 2016. They've built seven properties so far — including the whimsical "Wizard's Hollow" and "The Perch" that's an elevated treehouse — on land they initially didn't know what to do with, they told Insider.

"We were sitting around watching 'Treehouse Masters' one night and Caroline said, 'Why don't we try an Airbnb treehouse because it's Asheville and it's such a cool little town?'" Mike, 65, told Insider.

"We started talking about it in 2015," Caroline, 45, said. "And at that point, the thought was just traditional treehouses, but it's evolved from there."

The couple later appeared on season two of DIY Network's "The Treehouse Guys" and built their first treehouse, "Sanctuary." They completed their newest addition, "Alchemy," an underground house with a hidden slide, this February.

Mike told Insider they were inspired to build "Alchemy" during a Pinterest search when they stumbled upon a photo of an underground bunker. The couple wanted to create an unexpected entrance for the underground home, so they settled on a camping tent.

"We thought, how cool would it be to have a tent sitting there and people pull up and think, what in the world is going on here?" he said of building the underground home. "And then they come into the tent and find the slide."

Caroline added that they wanted the Airbnb to look "solely like a tent" outside.

Caroline and Mike said it takes them six to eight months to build a fully equipped treehouse, but that time varies depending on the project. They said "Alchemy" cost about $300,000 to build.

As of Friday, the property is available to rent on Airbnb for a nightly rate of $396.

Mike said the slopes on their land initially seemed like an obstacle.

"Our land is really sloping and that's why, initially, our land planner didn't think that property was good for anything," Mike said. "But it's perfect for giving people that treehouse feel or that underground feel."

While their first property, "Sanctuary," is built like a traditional treehouse, others like "The Aerie" are built on stilts. "Dragon's Knoll" and "Alchemy" are both underground builds.

Caroline said creating an underground home like "Alchemy" was similar to a building a basement.

One challenge Mike and Caroline said they faced with their business, like many others, was the fallout from the COVID-19 pandemic. For example, they said that when a contract worker contracted COVID-19, the project was shut down for two weeks. They also had issues getting materials they needed, Mike said, due to supply shortages.

Another challenge was creating the property's roof, which they said needed extra attention to ensure its measurements and placement were correct. Mike said they made a framework for the roof, enforced it with steel beams, and then poured the concrete into the framework.

"It's critical," he added. "A steel beam is not like a wooden beam that can do different things. Once you've cut that steel beam, it's cut and it better be right and in place."

The tent is placed atop the home's roof, so guests can venture into the tent and then slide into the Airbnb: a one-bedroom house that sleeps four guests with a queen-sized bed and a foldout futon.

Caroline told Insider that she and Mike wanted the tent motif to extend inside the home, so they covered the ceiling and walls with various fabrics from a warehouse in South Carolina.

"Keeping in mind that the inside should appear to be a tent, we surely didn't want to use Sheetrock walls," Caroline said. "I bought yards and yards of fabric to put on the walls."

"We tied knots in the fabric and put flags around the top to make it more whimsical," Caroline added.

Like all of the couple's properties, the Airbnb has heat, electricity, air conditioning, and full plumbing, they told Insider.

The kitchen has cooking utensils, a microwave, a refrigerator, and a coffee machine, according to the Airbnb listing. Guests can sit near the counter or at a table near the windows.

The home also has a bathroom with a shower.

Caroline and Mike said "Alchemy" was outfitted with expansive windows in the kitchen so guests can catch a glimpse of the Blue Ridge Mountains each day.

In addition to hanging fabric on the walls to make the underground home feel like a tent, Caroline and Mike overlapped several rugs on the ground to give the space a cozy feel.

Caroline said she cut old rugs and laid them across the room, then hot glued them into place.

Near a side entrance of the home — which guests can use if they would rather not use the slide to get into the underground Airbnb space — is "Enchantment," a separate tent pitched next to an outdoor sitting area with a firepit.

"People have really taken to it," Caroline said of visitors' response to the property.

"Magical stay! There is no place like this!" one former guest wrote in a review from June published on the property's Airbnb listing. "Home was extravagantly decorated but also extremely clean. Views were breathtaking and slide entrance provided much fun!"

A former guest wrote in another review from May: "My kids and husband were so surprised when they saw the tent and thought that was it. The slide and all the fun details WOWed not only my kids but us adults as well."

TikTok user @hannahsshoes, a friend of the Parrishes, has also praised the property. She shared a video of her stay at "Alchemy" in March 2022 to her 78,000 followers. As of Tuesday, her video has 3.6 million views and 721,000 likes.

You can find out more about "Alchemy" on Treehouses of Serenity or Airbnb.