A U.S. Coast Guard spokesman says the ferry headed to Provincetown ran aground Saturday morning near Nixes Mate, one of the smaller islands in the harbor.
Rescuers spent more than an hour and a half transferring passengers, crew members and the dog to another ferry.
Sgt. John Kelly of nearby Quincy says crew members told authorities that it was very foggy.
The Coast Guard will investigate.
An executive with Bay State Cruise Co. that owns the ferry did not immediately comment.
The Coast Guard says the ferry is expected be afloat again at the next high tide Saturday evening.