A 23-year-old teacher who vanished days before the school year began leaped from a pier into a harbor yesterday and was rescued by a ferry captain, police said.

Hannah Upp, who jumped into the chilly waters of New York Harbor around noon, was hospitalized in stable condition. She was undergoing a psychiatric evaluation and refused to speak to detectives.

The ferry was headed from Manhattan and was about a mile from Staten Island when Ms. Upp was spotted in the water, the chief police spokesman, Paul Browne, said. The ferry captain deployed a rescue craft, and crew members pulled Ms. Upp to safety.

Ms. Upp was found wearing a tank top and shorts, the clothes she had on when she was last seen August 29 at her upper Manhattan apartment. She apparently had planned to go away for the weekend, and when she didn’t return her roommates called police. There were no signs of forced entry into her apartment, and her wallet, keys and subway fare payment card were found inside.

Her disappearance prompted a citywide search, with Crime Stoppers and the United Federation of Teachers offering a reward of $12,000. More than a week after Ms. Upp vanished, she was spotted checking her e-mail twice at an Apple store in midtown Manhattan. She showered eight times at several city New York Sports Clubs, where she had a gym membership, police said.

Yesterday she was spotted at a Dunkin’ Donuts shop near the Staten Island ferry terminal. Police reached the coffee shop and heard a commotion at the terminal, where they found her being pulled to safety.

Ms. Upp, who is from near Portland, Oregon, was about to start her second year teaching Spanish at the Thurgood Marshall Academy and was a Teaching Fellow.