Fierce winds overturned the vessel, CNN reported. Rescuers plucked 22 people from the water, including a woman who later died at a hospital. The water temperature was 46 degrees -- low enough to cause hypothermia.
At least three crewmembers were on the boat, owned by Seaport Taxi. A captain and an assistant captain were among those rescued.
Although the craft was equipped with life jackets, fire and police officials believe the intense storm overtook the boat so rapidly no one had time to put the jackets on before the boat was overturned.
Water taxis transport visitors to several destinations in the Inner Harbor, such as the National Aquarium and Fort McHenry, where in 1814, Americans' defense of the fort against the British inspired Francis Scott Key to write "The Star-Spangled Banner."