A bizarre underground mystery is unfolding in New York City after multiple groups of people were caught on surveillance cameras entering and emerging from the city's vast sewer system during late-night hours. The strange incidents, recorded in Brooklyn and Queens, have sparked widespread speculation online and drawn the attention of the NYPD. In one particularly alarming video from Williamsburg, Brooklyn, approximately seven people were seen climbing out of a manhole in the middle of a busy intersection as traffic passed by. While authorities say there is currently "no threat to the public," police are investigating the unusual sewer activity, leaving many residents wondering what exactly was happening beneath the streets of America's largest city.