Boston Harbor made the city, chosen by John Winthrop in 1630. When John Winthrop arrived in 1630 with the Massachusetts Bay Colony charter and 700 settlers, he chose this harbor because of its natural depth, its protection from the Atlantic, and the three hills behind it that provided high ground for defense. Boston quickly became the premier port of British North America, its merchants trading with the Caribbean, Africa, and England in a web of commerce that included sugar, rum, slaves, codfish, and manufactured goods.
The wharves that stretched into the harbor were the economic engine of colonial America. By 1740, Boston was the largest city in the colonies and its harbor the busiest port. The harbor's history includes the Tea Party of 1773, when the tea dumped here floated on the surface for weeks; the Siege of 1775-1776, when British ships blockaded the harbor; and the industrial era, when the harbor became so polluted that Boston Harbor was called the dirtiest harbor in America.
A federal court order in 1985 mandated a cleanup; the Boston Harbor Project, completed in the 1990s, was the largest urban harbor cleanup in the country's history. Today the harbor is clean enough for swimming. Find the ferries to the harbor islands; they have been state parks since 1996.