The woman, who was described as distressed, climbed over a fence at Pier 11 and jumped into the water, said Rod Roy, 34, who works for a helicopter tour company and was standing at the pier at 9:47 a.m. Friday.
"She goes over the banister like she was climbing down a ladder," he said.
"The next thing I know, she's panicking and screaming."
Roy said he sprinted to a fire station a block away, yelling for help. Emergency services were on the scene quickly and pulled her out of the water, the FDNY said.