On a sweltering day earlier this summer, Marcellus Cadd was standing in a trendy neighborhood in downtown Austin.
His phone told him he was 20 feet from an object he was honing in on using GPS coordinates. He walked over to a bank of electrical meters on a building, got down on one knee, and started feeling underneath.
"Holy crap, I found it!" he said as he pulled out a small metallic container. Inside was a plastic bag with a paper log. Cadd signed it with his geocaching handle, "Atreides was here."
Cadd is one of more than 1.6 million active geocachers in the United States, according to Groundspeak, Inc., which supports the geocaching community and runs one of the main apps geocachers use.
Every day for the past three years, he has taken part in what is essentially a high tech treasure hunt. It's a volunteer-run game: some people hide the caches, other people find them.
But soon after he started, Cadd, who is Black, read a forum where people were talking about how they were rarely bothered by the police while geocaching.
"And I was thinking, man, I've been doing this six months and I've been stopped seven times."
As a Black person, Cadd said those encounters can be terrifying.
"Nothing bad has happened yet, but the worry is always there," he said.
It's not only the police who question Cadd. Random strangers - almost always white people, he says – also stop him and ask why he's poking around their neighborhood.
Geocaches are not supposed to be placed in locations that require someone looking for them to trespass or pass markers that prohibit access. And by uploading the coordinates of a cache page to the geocaching app, the hider must agree that they have obtained "all necessary permissions from the landowner or land manager."
Still, Cadd avoids certain caches — if they are hidden in the yard of private homes, for example — because he feels it could be dangerous for him. And while hunting for caches, he uses some tricks to avoid unwanted attention, like carrying a clipboard.
"If you look like you're working, people don't tend to pay attention to you."
He writes about encountering racism on the road on his blog, Geocaching While Black. He's had some harrowing encounters, such as being called "boy" in Paris, Texas. Or finding a cache hidden inside a flagpole that was flying the Confederate flag.
Such experiences may be why there are so few Black geocachers. Cadd says he often goes to geocaching events and has only ever met one other geocacher in person who is African American (though he has interacted with a few others online).
Bryan Roth of Groundspeak said that while there is political and economic diversity among the hobbyists, people of color are greatly underrepresented. He said Groundspeak often features geocachers of color on its website and social media, in order to encourage more to participate in the game.
Geocaching is built upon the idea of bringing people to places where they wouldn't be otherwise. Roth, who is white, acknowledged that race can play a role in how people poking around such places are perceived.
"Geocaching is just one small part of that. It will take a fundamental shift in society" to get rid of that bias, he said.
Roth said he hopes that as the game becomes more popular there will be less suspicion of geocachers.
For Cadd's part, he said he gets too much joy from geocaching to let bias drive him away from the pastime.
"I've seen so many things and I've been to so many places. Places I wouldn't have gone on my own," he said, adding that he hopes his blog will encourage "more people who look like me to do this."
"There's a certain joy in being Black and basically going out to places where you don't see a lot of Black people. And being there and being able to say, 'I'm here whether you like it or not.'"
Cadd has already found more than 3200 caches since he started, including at least one in each of the 254 counties in Texas. His lifetime goal is to find a geocache in every county in the United States.