Whalewatching from Gloucester about 20 miles north of Salem or you can catch the ferry from Rowe's Wharf on Boston's waterfront. Various companies operate daily trips but to the feeding grounds of humpback, fin back and other whales Yankee Fleet is one of the better known.
Allow half a day for the boat trip the cost is about $25 for adults, $15 for children. Gloucester itself is a great place to eat lobster, and you can also visit the Hammond Castle Museum home of the man who patented over 400 inventions, including the car starter, electric toy trains and shaving cream.