This is an archived article that was published on sltrib.com in 2016, and information in the article may be outdated. It is provided only for personal research purposes and may not be reprinted.

In a hidden cavern, sunlight breaks through the top to catch the steam rising from an ancient pool. The dark blue water hides its cavernous depth. It's the greatest hot tub in all of Utah.

At least, that's how the Crater is billed on Atlas Obscura, the online database of interesting places to see around the world, from ghost towns to natural phenomena. The Crater, also known as The Homestead Crater, is a popular geothermal pool at The Homestead Resort in Midway. And on April 16, Atlas Obscura wants to celebrate the natural wonder with a dip.

Atlas Obscura has booked a private hour, from 11:30 a.m. to 12:30 p.m., for people to soak in the Crater's cavelike pool. (Tickets are on sale for $16.) The event is one of more than 200 Atlas Obscura is organizing around the world as part of its annual Obscura Day, a celebration of the odd or amazing sites people can discover when they go exploring.

In 1996, a tunnel was burrowed through the limestone to give swimmers and divers access to the Crater's warm waters, which hover between 90 and 96 degrees. Divers can "descend 55 feet into the hourglass-shaped depths," according to The Homestead's website.

The cave's beehive-shape, calcium carbonate dome grows at a rate undetectable to the human eye, "thanks to eons of mineral deposits left on the cave walls by the continuously rising steam from the spring's balmy waters," according to Atlas Obscura.

Besides bringing a swimsuit and towel, Atlas Obscura recommends arriving early so visitors have lots of time to check in.

Last year, Obscura Day in Utah highlighted the Bonneville Salt Flats. Other Utah locations on Atlas Obscura's map include the Delta solar panel ruins in Millard County, the Mars Desert Research Station in Wayne County and the ghost town of Sego in Grand County.

For a full list of Obscura Day events, visit atlasobscura.com/obscuraday2016.

Twitter: @MikeyPanda —

Obscura Day at the Crater

The Homestead Resort is located at 700 N. Homestead Dr. in Midway. Tickets for the private dip, from 11:30 a.m. to 12:30 p.m. on April 16, cost $16.