Indiana man turns napkin pool sketch into 60,000-gallon backyard water park

Plenty of people dream about a backyard pool. Cory Johnson built a water park. On the east side of Lake Wawasee in Cromwell, his home shares its grounds with a 60,000-gallon private retreat that has waterfalls, a slide, a zip line and real palm tree trunks.

Then he rents it out for $140 an hour!Walk in, and the first question is how anyone fitted a lagoon into a backyard. The second is obviously when you can book it!

He wanted a pool, but they asked him to wait

Like many others, Cory Johnson wanted a backyard pool where he could relax on the lounge chairs and enjoy his days. He initially set out to get a pool. A few years ago, he learned that the installation wait would stretch to about a year and a half, according to a report by inkfreenews.

Rather than sitting around, he started sketching what he wanted on a napkin. That took him down memory lane.

Ever since The Legend of Billie Jean came out, he had wanted a pool that he could jump into, or perhaps slide into straight from the house. "I watched the movie 'The Legend of Billie Jean' back in the '80s. (In) one of the scenes, a guy slides out of the window. He slides out of the window right into a pool. I said, 'I want to do that.

I'm going to build that someday,'" he told Goshen News earlier.So, when he discovered that he would have to wait another year for the pool installation, he thought he would build it himself. "It can't be that hard," he told the outlet.

Two pools in two years

The outdoor pool went up using blocks mortared together and reinforced with rebar. Johnson built the walls himself. Contractors poured the foundation, and Amish brothers finished much of the structure.

The work took two years, including a six-month break in between. Both pools were finished in September 2023.The indoor pool took four days to fill! Cory Johnson's wife, Mandy, who was part of the project from the start, remembers checking the water line every morning. "Every morning, we'd wake up and come out here and see where the water line was. It was just neat every day to watch it fill up."The indoor/outdoor pool holds about 60,000 gallons of heated salt water, maintained at between 85 and 87 degrees year-round.

Two pumps, two salt generators and oversized filters keep the water clean. Johnson still wants to cut back on chlorine, so he's thinking about adding a UV and ozone system.

Inside the private

The indoor pool has a lagoon aesthetic. Fresh water rains down from a perforated pipe in a ceiling 20 to 30 feet up. A waterfall pours over giant rocks behind it. There is a zip line that sends guests flying towards them before they drop safely into the water.The custom slide is what catches people off guard. It ends higher above the water than most expect, so the ride is faster than they planned for. It sits on a 5-inch stainless steel pipe reinforced with concrete and rebar, then covered in stone so that it blends in. Mandy calls it a "beach vacation oasis".

You can rent it for $140 an hour

Cory Johnson's pool in Cromwell won Swimply's Choice Award for 2026 for its distinctive design, which recreates the look of a waterfall landscape and incorporates natural outdoor elements into the pool area.Today, the Johnsons rent it out for $140 an hour. On average, they get five to six bookings a day. They also provide snorkelling gear, pool toys and professional underwater scooters used by scuba divers.The couple never planned to rent the pool. They hadn't even heard of Swimply when they started building. Now they rarely use the pool themselves, except for cleaning and maintenance.Mandy says many first-time guests don't believe the pool is real until they see it! One guest, who usually booked hotels or visited attractions for their daughter's birthday, said the experience at Johnson's property was the best yet.

"This place is amazing! Every year for my daughter's birthday, we usually get a hotel so her friends and family can celebrate and swim. We have gone to Kalahari Yogi Bear camp ground ect.

My daughter said this was the best birthday ever!" the review on Swimply reads. Another agreed: "The best space for a party! My son and his friends had an absolute blast. The host was also so laid back and pleasant to talk to. 10/10 would rent again and would recommend!"The pool stays open all year, so the Johnsons decorate it for winter with a 14-foot Christmas tree. Mandy says the children who walk in see the tree and the pool together, and it's "just like a double win for them".Cory Johnson isn't done. He's already dreaming about a steam cave and a hot spring that runs hotter than normal. "That'll probably never happen, but you never know. We don't like little. Go big or go home," he told the outlet.