The Coast Guard says a 55-year-old man spent about 20 minutes in the 38-degree waters of Portland Harbor after falling off a ferry.
The man, whose name was not made public, was rescued by a fishing vessel at about 5:15 p.m. Tuesday.
He was taken to Maine Medical Center for treatment of hypothermia.
The Coast Guard says the man told them he was on the Peaks Island ferry when he fell overboard. He was spotted by the fishing vessel Christina & Caelyn. The vessel's captain called the Coast Guard then pulled the man to safety.
Coast Guard Lt. Connan Ingham says the man "is lucky to be alive," and praised the fishing boat's crew for their quick response.
The incident remains under investigation.