BLOCK ISLAND, R.I. — In a forest here, Katie Hall and members of her extended family were dangling her mother’s bra into a hollowed-out tree trunk with the laser focus of open-heart surgeons. When that failed, Ms. Hall, her mother, brother, aunt and cousin untied their shoes, using the laces to form a makeshift net in the hopes of picking up something just out of arm’s reach. Two hours of MacGyver-ing and one downpour later, success arrived, with the help of a spaghetti spoon taped to a branch.

On another part of the island, Dawn Holmes walked back up a dirt path after completing her mission. A group of women approached, still reeling from getting lost at Rodman’s Hollow without cellphone signal. Ms. Holmes lingered casually, adjusting her now empty backpack. When the women discovered what she’d hidden, screams of glee pierced the air.

Hundreds of beautiful handblown glass fishing floats are scattered across the wilderness of Block Island each year, attracting an underground society of fanatics who will stop at nothing to find them.

These are the orbivores. Eben Horton is their Pied Piper.

“I love the term ‘orbivore.’ They call them orbs. Technically they’re floats, but sure, they’re orbs,” Mr. Horton said, with a laugh. “It’s like a tribe. I’m absolutely amazed and humbled and proud but, like, what have I created? Am I a cult leader? I had no idea that this would turn into this.”

Mr. Horton, a 46-year-old glass artist, started the Glass Float Project in 2012 as a whimsical scavenger hunt, just for fun. He spent his childhood sailing the 12 miles from mainland Rhode Island to Block Island, a 7,000-acre dot in the Atlantic. For roughly a century, foreign fishermen attached glass floats to their nets. The floats inevitably detached and traveled across the sea, washing up in fated spots after unimaginable journeys. Mr. Horton, an avid beachcomber, loves mulling the history of these pieces.

The first year, Mr. Horton handmade 150 glass floats at his studio in Wakefield, R.I. The event began that June, gathering unanticipated momentum with locals and tourists. Block Island swells from under 1,000 year-round residents to roughly 20,000 visitors per day at the height of summer. People come for the beaches and restaurants, but most never explore the deceptively wild and desolate natural areas. The scavenger hunt became a gateway to a different world.

Now in its eighth year, the Glass Float Project has worked its way into the daily flow of Mr. Horton’s gallery. While waiting for the furnace to get hot each morning, he, his wife, Jennifer Nauck, and their two assistants fill in time gaps by making floats.

The four-person crew makes 550 highly coveted floats each year. They etch the year and a number onto each with a Dremel bit. Most are clear glass. The annual No. 1 typically has gilding.

A certain amount (corresponding with the current year) are colored. Found floats are registered on the island’s website to keep track of what’s still at large. Orbivores are held to an honor system: only one float per person per year, to keep things fair.

Hunting the Rona

For 2020, Mr. Horton felt inspired to create something beautiful and lighthearted in a year that has been anything but. This year’s No. 1 is a colorful coronavirus particle, which he calls “the Rona.” A typical glass float takes 10 minutes to make, but the Rona took Mr. Horton several hours.

The orbivores went wild, asking whether he would make more available for purchase. As a compromise, Mr. Horton created a second Rona to be raffled off, with proceeds helping to fund future floats.

The Glass Float Project (which costs an estimated $20,000 per year) is funded largely by donations with help from the Block Island Tourism Council. Mr. Horton has been offered plenty of opportunities to sponsor the project, but he steadfastly refuses to commercialize it in any way. It is an art adventure for the people, and he intends to keep his labor of love humble.

While orb hunting is a year-round activity, Mr. Horton starts each summer “season” by packing a box of 100 sturdy glass floats onto his sailboat and heading to Block Island, like some kind of seafaring Santa Claus. He is easily recognizable and highly accessible, through both his glass studio and an online group he started. The orbivores openly adore him, which has some drawbacks when it comes to covert operations like hiding.

“These orbivores know what he drives, what he sails, they constantly see him,” said Jessica Willi, the director of the tourism council. “If he’s coming to Block Island, they’re coming to Block Island. Poor guy can’t go anywhere.”

Ms. Willi is one of several top-secret friends Mr. Horton trusts to help hide orbs. Over the years, she’s had to make some life adjustments. She uses a different car when she hides, so nobody recognizes her. She tries not to post photos of her leisure walks, because her more suspicious friends have rushed in after her.

“Everyone on the trails thinks that if you’re not hunting, you’re hiding,” she said. “The orbivores have their special walking sticks they poke in the bushes, because there’s poison ivy. They have their water bottles. They pack lunches. They’re prepared.”

To dodge them, Ms. Willi has occasionally ventured out in the dead of night with only a headlamp. Darkness didn’t stop Katie Nelson, 53, a retired sales and marketing director from Montana who once hunted under a full moon with her flashlight in the hopes that the light would reflect off any glass. (It rained, and she returned empty-handed.)

Hiding spots are completely up to the hider, outside of some logistical rules that developed over time. There is no hiding on private property, near the school or in any environmentally sensitive areas (like the dunes, beach grass or bluffs). Everything else is up to chance. Even Mr. Horton has no idea where most of the orbs are. He prefers it that way, to keep himself honest when orbivores attempt to pry him for information.

“Sometimes I’ll put a smaller one in a fisherman’s glove on the beach, or in a lobster pot,” Mr. Horton said.

“Twice, I’ve dropped some off the ferry so they’d wash up on Block Island. One was found later on Long Island,” he said. “At that point, am I littering? Is that cool or is it bad? I don’t know.”

Mr. Horton likes hiding spots where the glass orbs are easy to see but hard to retrieve. He frequently hides some in an island cannon, because they roll all the way to the back.

Tricia Serio, 50, a professor and dean at the University of Massachusetts Amherst, who lives in Leverett, Mass., was driving back from an ice cream date with her husband and two sons when her boys suddenly insisted that she stop the car near a cannon. One hour (and lots of screaming) later, the mosquito-bitten foursome was still standing around in the dark debating how to get a float out.

“I went to our rental house and brought back a ladle and some duct tape, which did the trick,” Ms. Serio said. “Everyone was ecstatic. Later that night that we remembered that they’re called floats and that we should have poured water into the cannon.”

After coming home orb-less on his first island visit in 2017, Bill Holbrook spent hours devising a “divide and conquer” strategy. He compiled five years’ worth of data from the town website, built queries to generate statistically relevant hiding spots and created a heat map of the island.

In 2018, he covered 22 miles in 48 hours, with no luck. In 2019, after another unsuccessful day left him physically and emotionally exhausted, his girlfriend, Lisa, suggested they head back via a stretch of sand near Payne’s Dock. There, Lisa casually found an orb hidden in an old tire.

“I now believe it’s more about karma than data,” said Mr. Holbrook, 52, a marketing director from South Weymouth, Mass. “Was this little stretch of sand on my heat map? No way. Was this little treasure meant to be found by Lisa? Absolutely.”

This is a common theme of orbivore stories: The floats appear when you least expect them to, or when you’ve lost your will, or when you need a little wink from the universe.

Last winter, Isaac Ariel, 67, a retired I.T. professional and Block Island resident, casually found a No. 61 float on the beach, two days before the 61st birthday of his orbivore wife, Susan.

“Finding a float is a bit like finding love,” said Ms. Holmes, a retired educator from Newburyport, Mass., who honeymooned on the island. “You have to be open to it and not try too hard, but then when the moment is right it finds you.”

Ms. Holmes, who is also a hider, found her first float unexpectedly after days of intensely scouring the trails. She spotted a snake in the grass one afternoon. After a brief moment of panic, she realized it was wrapped around a float, like it was some kind of glass apple in the Garden of Eden.

Mr. Horton likes to say that the point to all of this is there is no point. It’s about the journey, being outside, enjoying the island. Orbivores may be obsessive, but they take that to heart. Some go so far as to restage floats they’ve found for their loved ones, like grandparents who can no longer walk far, or small children with high hopes.

In 2018, Nicole Dorfman’s boyfriend at the time, Mark, hatched a plan to propose via orb. He ordered an inscribed float through Mr. Horton’s studio, then sneaked it into a spot alongside some canoes at Fresh Pond.

“I found it and obviously said yes, but I knew it didn’t truly count since it wasn’t a real orb,” said Ms. Dorfman, 27, a third-grade teacher from Schaumburg, Ill., who has been searching since 2012. Last July, after an anniversary dinner celebration, she and her family stopped by Island Cemetery on a whim. She found an orb between a rock wall and a tree.

The orb hunting Facebook group (started by Mr. Horton) is a rarity on social media: thousands of strangers with a common obsession and no off-topic rants. It is a hyper-focused, passionate community that somehow — even in 2020 — remains supportive and positive.

People post photo updates of their seeking missions. Fellow orbivores celebrate their successes and lament their failures. Occasionally, Mr. Horton will pop in with a clue, which he believes ruins the fun, but the group disagrees so he acquiesces.

Leah Melius, a 38-year-old physical therapist from Essex, Conn., has been orb hunting with her family since 2012. One day in 2017, her phone dinged with a new hint on the Facebook page, where Mr. Horton had posted a photo with a jetty she recognized. They piled into two cars and sped across the island from Mohegan Bluffs to Charleston Beach.

“We felt like we were on ‘The Amazing Race.’ We couldn’t believe our eyes when it was still there!” said Ms. Melius, whose mother now displays the float proudly in her living room. “Everyone was cheering and high five-ing and crying tears of joy.”

Josie Lawrence, 15, has been orb hunting since she was 9. She was unsuccessful until 2018, when after an online hint and some quick sleuthing, she and her mother raced over to the beach near the North Light lighthouse. With no orb in sight, they watched a seal play offshore instead. On the way back to the car, Josie noticed something glinting inside a log.

“At that moment I started crying,” she said. “Though it took a lot of time and hard work, all the summers of long walks and hikes have been completely worth it.” Mr. Horton and his hiders enjoy keeping up with the orbivores online, where they get to put a face to a found float. He thinks a lot about how this project took on an effortless life of its own and why it resonates so deeply with so many.

“I think people want answers for everything in life now,” he said. “The thing with the glass floats is there are no answers. You don’t find them, they find you.”

“It’s all just a magical thing. People want answers but people need some magic.”