WMTW-TV reported two people who witnessed the crash Friday afternoon jumped into the water and pulled the woman to safety through the car's back window.
The car went out of control on India Street, crashing through two fences before splashing into the water next to the cruise ship Yorktown.
The Portland Press Herald quoted emergency workers as saying the driver may have suffered a medical problem. Her condition was not known.
(Copyright 2012 by The Associated Press. All Rights Reserved.)