BOSTON — Want to learn about American history?

Take a boat ride in Boston Harbor — and get ready to listen as well as look.

The "Birth of a Nation" cruise highlights the historical significance of Boston Harbor before and during the American Revolution. An audio tour features stories about episodes like the Boston Tea Party, Paul Revere's ride and the Battle of Bunker Hill.

From the top deck of Seaport Belle, a replica steamship, passengers can peer down the channel to the right and imagine tea chests crashing into the water during the Boston Tea Party. Actors portraying characters from the period explain on the audio tour how in 1773, colonial activists boarded East India Company ships and dumped 1,800 pounds of tea overboard in protest of a tea tax imposed by the British.

Also narrated is the tale of Revere's ride, west from Boston, and his famous warning to colonial leaders: "The British are coming!"

The story notes that Revere was captured by British soldiers before he left Lexington.

"He got caught," said Steve Woods, visiting Boston from England and taking the cruise with his wife and daughter. "I didn't know that."

The tours depart from Rowes Wharf and are run by Massachusetts Bay Lines Inc., which also operates whale-watch cruises and commuter ferries between Boston and Hingham.

Airplanes rise from Logan International Airport as Seaport Belle turns away from the South Boston docks and heads directly toward Charlestown, home of Bunker Hill and the USS Constitution.

The steamship, which runs on the hour during the day, stops briefly in the Charlestown Navy Yard. Passengers can get off and return on any future tour later in the day.

Along the tour, don't be fooled by the laundry-detergent bottles bobbing in the harbor. Those are lobster-pot markers. They're cheaper than wooden buoys.

Long after the tea was dumped, Boston Harbor became the dirtiest in the nation because of sewage. But it has undergone a $4.5 billion cleanup since the late 1980s. A decade ago, the 34 harbor islands were added to the national park system.

Seaport Belle Captain Wesley Babbitt said the harbor is much cleaner now than when he started 10 years ago.

"I notice a lot less debris, certainly, along the sides at low tide," Babbitt said, motioning toward the seawall near the General Ship drydock in South Boston. "There's much more marine life that comes into the harbor — a lot more harbor porpoises during the winter. Seals come in the spring."

While fewer European tourists take the tour now than before the 9/11 attacks, the drop in business has been partly offset by an increase in Chinese visitors. Jay W. Spence, general manager of Massachusetts Bay Lines, estimates 40,000 Chinese-speaking passengers will take the tour or go whale-watching this year.

And that's why, in addition to offering the audio tour in English, French and Spanish, it is also offered in Mandarin.