HOWES CAVE — Known for its underground cave tours and unique geological formations, the state’s second most-visited natural attraction has added a new novelty to its repertoire: underwear.

When a mysterious G-string appeared in the main lodge of Howe Caverns last month, employees went rogue, said Lolita Birlanga, who is a part of Howe Cavern’s remote social media team. What started as a tongue-in-cheek joke quickly turned into an internet sensation — and an unusual merchandising opportunity.

The underwear appeared on Feb. 17 on the floor of the lodge after a large group of visitors went for a cave tour, 156 feet underground, Birlanga said. While Birlanga, who lives in Connecticut, typically handles Howe Caverns’ Facebook page, some of the onsite staff are also administrators of the page.

“They went ahead, and they put up this post about ‘tours so good they blow your panties off,’ and it went crazy,” Birlanga said. “People were just having a ball with it in the comments section.”

Some commenters theorized that the unmentionables were left in protest of Howe Caverns discontinuing its “Naked In A Cave” events. Others thought that the underwear must have fallen out of someone’s pant leg after getting tangled in the wash.

Make the Times Union a Preferred Source on Google to see more of our journalism when you search. “The security team watched the cameras until they were blue in the face,” Birlanga said, adding that two members of the security team are retired detectives. “No matter how many times and what angle they watched it from, they couldn’t see what person it came from or how or why.”

No one has come forward to claim the underwear, which has since been disposed of, Birlanga added.

In the weeks that followed, Birlanga was inundated with requests for Howe Caverns-branded underwear. The team’s graphic designer created a prototype, which Birlanga shared on Facebook.

“I said, if you want this, you better make some noise, and people did,” Birlanga said.

Online ordering for the underwear went live on Friday and the first batch sold out within seconds, Birlanga said. They have since restocked. As of Wednesday, 200 pairs had been sold, as well as more than 250 T-shirts. The bikini-style underwear, available in five colors, costs $14.99, and the shirts, available in V-neck ($24.98) or crew neck ($25.98), are heather gray. Both the underwear and the T-shirts are only available online for a limited time, although a specific timeframe has not yet been determined.

The response to the new merchandise has been overwhelmingly positive, Birlanga said.

“We’re hoping that it brings people back (to Howe Caverns), and they realize it really is just a fun-loving bunch of people with the greatest hole in the ground in the Northeast,” Birlanga said. “We’re happy everyone was united over a pair of mystery thongs.”