It was 2 a.m. and Aki Jakupovic was working in his auto repair shop in Queens when he made eye contact with a group of men lowering themselves into the sewers just outside.
“I knew they were up to no good,” Jakupovic told NBC News. “They just looked up, look down and continued like I wasn’t there. You know, I’ve seen a lot of crazy stuff in New York, but this was really something.”
Jakupovic compared these men to the Ninja Turtles, referencing comic book characters who live in the New York City sewer system.
“Three random guys walking around in a strange suit. Open the sewer, go in like the Ninja Turtles,” Jakupovic said.
This was the first of three unexplained sewer incidents reported in Brooklyn and Queens since early May.
What is causing people to descend into underground manholes in the middle of the night? What are they doing in the hours they are down there? And why has this odd phenomenon been happening for centuries?
The mystery remains as officials continue to investigate, but some theories have been put forward.
Multiple groups have been seen popping in and out of manholes, some with shovels and headlamps in hand
Following the incident Jakupovic witnessed on May 5, more than a dozen people, none of whom are affiliated with public works crews, were seen exiting two manholes in Brooklyn on May 29.
One group of at least seven people were seen entering the sewers around 11 p.m. on May 28 and emerged around 2 a.m. the following day, May 29, authorities said. All of them appeared to be wearing coveralls or other protective clothing, which they quickly changed out of.
Another group was seen entering a manhole 8 miles away around 1 a.m. on May 29 and climbed out just before 4 a.m. At least three of the men were carrying shovels and all were carrying or wearing headlamps. The men immediately escaped in a vehicle.
Investigators have not linked the two incidents.
NYPD and other agencies investigated the area following the sighting and said the area was safe. No nefarious items or damage to the sewer system was found during the investigation, according to a senior law enforcement official.
Anthony Purdie, a Brooklyn resident, said the men must have motivation beyond “simple curiosity.”
“They look like they were looking for something important, like money, or for doing some type of hurting,” Purdie told The Associated Press. “Ain’t no fun and games. I mean, seven grown adults going down there? Got to be something, man.”
Police say the leading theory is that the group is searching for items of value that may have been lost in the sewage.
Odd activity has been taking places in New York sewers for centuries
This is not the first time suspicious activity has been detected in New York’s sewer system. Exploration of New York manholes dates back to the 1800s, according to a series of articles by The New York Times that tell stories of the sewers filled with escaped convicts, missing pets, drugs, gems and even unopened mail dumped by temporary postal workers.
In 2015, a city worker and two friends were given criminal trespassing charges for descending into a Brooklyn manhole to look for “gold, jewelry and guns.”
Three men were arrested in April 2025 for entering the Brooklyn sewers. Willer Green, one of the arrested men, told police at the time, “The reason we went down there is that people lose their gold there. We got to sell it to make money.”
Unusual activity extends beyond just exploration.
Manhole cover theft was on the rise in 2012 in Brooklyn, Queens and the Bronx. More than 30 manhole covers went missing between March and May, some weighing as much as 300 pounds. Normally, only two or three manhole covers go missing in a single year.
A 2022 manhole cover explosion in Times Square caused chaos as people screamed and ran from the sight. Firefighters from the New York City Fire Department arrived on the scene to find three manholes on fire.
Most recently, the sewer system was the unplanned destination of 70 teen girls on a school field trip in Nyack, New York, on Wednesday. The students entered a drainage culvert near Nyack’s central business district. Later, a police officer from Orangetown saw them exiting an alley sewer grate and alerted local authorities. All of the girls exited safely and without serious injury.
Officials warn about the dangers of ‘sewer scavenger hunts’
Sewage often contains bacteria, viruses and parasites that can cause severe illness. Sewers also pose risks such as low levels of oxygen, confined spaces and possible electric shock.
“Entering the sewer system is both illegal and extremely dangerous,” said a spokesperson for the city’s Department of Environmental Protection. “Members of the public should never enter a pipe, drain, catch basin, manhole, or outfall.”
Council Member Susan Zhuange said sewers are “not a place anyone should ever enter.”
“To anyone tempted to explore these spaces: it is not worth your life. If you see someone entering a manhole, call 911 immediately,” Zhuang said in a statement.