The Inner Harbor is the portion of the harbor inside of Castle Island and includes Boston, East Boston, Charlestown, Everett and Chelsea.  The Mystic River, the Charles River and the Chelsea River (also known as Chelsea Creek) all feed into the Inner Harbor.

The Outer Harbor stretches to the south and east of the Inner Harbor.  The Outer Harbor is made up of three large bays:  Dorchester Bay, Quincy Bay and Hingham Bay.  Several rivers, including the Neponset River, Weymouth Fore River, Weymouth Back River and the Weir River, feed into the Outer Harbor. 

Boston Harbor contains a considerable number of islands, most of which are part of the Boston Harbor Islands National Recreation Area. The following islands exist within the harbor:

 

 

Two former islands, Castle Island and Deer Island, still exist in a recognizable form. Castle Island was joined to the mainland by land reclamation, whilst Deer Island ceased to be an island when the channel which formerly separated it from the mainland was filled in by a hurricane in 1938.

Two other former islands, Apple Island and Governors Island, have been subsumed into land reclamation for Logan International Airport.

Before the establishment of the Boston Colony by John Winthrop in 1630, the harbor was a trading post for Native Americans in the region.  With the colonization from England, a local shipbuilding industry was started and the port began handling trade from the colonies and from Europe.  As the Colonies grew during the 1700s, the ports of New York and Philadelphia eventually  surpassed Boston in inter-colony trade.  Boston merchants established trade with

The Liberty and other tugs can be seen anywhere in the Port of Boston and surrounding waters at any time.  In addition to the liquified natural gas (LNG) tankers that call on the Distrigas facility in Everett.  There are  oil and salt terminals in the Chelsea Creek.  Boston Auto Port in located at the old Moran Terminal in Charlestown.  Both Exxon and Prolarized scrap are in Everett.  Conley Terminal and Black Falcon Cruise Terminals are in South Boston along with Boston Ship Repair.  Citgo and Deepwater are located in Braintree and Quincy