The bees showed up and took over the hydrant at Fulton and Front streets around 11 a.m. Saturday and stayed for several hours until police arrived, the New York Post reported.
New York Police Department bee specialist Anthony Planakis, who vacuumed the swarm using a special device designed to keep the bees safe, estimated there were about 17,000 bees in the swarm and said he found the hive's queen among them.
Police said they believe the bees escaped from a rooftop bee-keeper somewhere nearby. Beekeeping has become a popular summertime hobby among New Yorkers.
"This is mad! I've never seen anything like it," said John Nye, 42, a London horticulturalist who was vacationing in New York.
Even New Yorkers said they were amazed by the sight.
"It's unusual. I've never seen anything like this," said Winston Small, 25, a bartender at a nearby restaurant. "I don't think I've ever even seen a bee at the seaport!"