If you have kids with you, Museum Wharf is a must. There you will find the Children's Museum and the Computer Museum. I had a hard time dragging my nephew away from the Children's Museum! Even if you don't have the kids with you, the Museum gift shops are great for gift ideas.
In addition to the museums, the Milk Bottle, Au Bon Pain and a deli on the same block on Congress St provide options for lunch on the Wharf. There are several picnic tables outside to enjoy the city skyline while you rest & refresh yourself.
Sit down by the harbor and watch the boats go by. There are lots of people out for pleasure, but Boston is a working harbor as well.
From Long Wharf you can jump on a whalewatching cruise, take the ferry to the Harbor Islands or Provincetown on Cape Cod (only in summer). You can also catch a water taxi to the airport.
The New England Aquarium and IMAX are located at Long Wharf as well.
Boston is a great city for walking. You can explore most of the downtown area on foot. Summer is a popular season with tourists, most of whom take the Freedom trail, which is a great idea. You can do the trail in its entirety, or you can take a short detour and explore Boston Harbor.
One of the oldest in North America, Boston Harbor hasn't yet experienced the transformation/renewal seen at other harbor city (like San Francisco's Pier 39). This is a blessing, as you can catch the winds and a view of the ocean on the wharf without being pestered by a tacky souvenir shop.
The mainstay of the Harbor is the New England Aquarium. Though not the biggest or the best in the world, it's charming and has many interesting exhibits. It's even the setting for a movie ("Next Stop: Wonderland"). On Long Wharf, there are many cruise ship operators that can take you for a tour of Boston Harbor, around the Harbor islands, or to Stellwagen Banks in the Atlantic for whale-watching. Once you're done, head to the North End for a sumptuous supper and dessert.
Boston Harbor has gone through troubled times, as most of it was unaccessible for many years. The area has been slowly revitalized, and you can now walk a great deal of it. You can start in the North End, near the Bunker Hill Bridge, and watch old men playing boules, then continue around Atlantic Ave. to Christopher Columbus Park, stopping to see the view of the harbor islands, and see the planes take off and land at Logan Airport. From here, you can walk to the Aquarium, where there are several cruise lines in operation. Further along you come to Rowes Wharf, with dinner and show cruise ships, and the Boston Harbor Hotel and Towers, then cross the old Northern Bridge to the Seaport District.
A perfect walk on a beautiful day, you can end with afresh seafood dinner, overlooking the harbor.
A very nice harbour and very special since it is so close to the centre of a major city. The harbour buildings have been renovated and are now beautifull appartmentbuildings. There are parks and statues along the harbour. Whale Watch tours start from here also. A very nice place to let your feet rest after completing the freedom trail. You can enjoy the view: boats, islands and Logan Int Airport (which is located right across the harbour.)
There are a lot of activities around the New England Aquarium area. There are boat rides from Long Wharf to other destinations. The "T" boat ferry has service to Boston Logan Airport. Just walk along State Street. There are a lot of interesting sites. Subway line: You can take the Blue Line to the "Aquarium" station or the Red line to the "South Station" station.
Great photograph spot. Unfortunately the museum was closed when I was there. On their web site it says there was a fire at the museum so it will be closed for the rest of the season. Pretty historic spot.
Boston Tea Party Ship
Please check the museum website for the whole story about the protest against taxes and dumping of the tea.
I loved this place as a child and made my mom take me there until I was about 13. There are so many different hands-on activities and my fondest memory has to be making my own dradel (excuse spelling). I really don't have a lot of other experience with children's museums, but this one will always be my favorite and is a great place to go if you have little ones.
Many great sight are located around the bay, however you will find great things everywhere in Boston.