Passengers lying on stretchers littered the pier near South Street Seaport, attended to by firefighters and rescue workers who rushed to the scene of the 8:43 a.m. (1343 GMT) hard landing.
"People were thrown into the air and onto the ground," passenger Elizabeth Banta told CNN. "There were definitely many people on the ground who were not moving."
Some of the injured were taken to the hospital, while others were treated at the scene, she said.
A police department spokesperson said one of the 57 people injured appeared to be in critical condition.
"The boat was backing up and hit something and that's when everything went crazy," said one witness, a construction worker who declined to be named, who was working nearby when the 400-passenger ferry slammed into the pier.