[1] The bay forms New England's largest estuary, which functions as an expansive natural harbor and includes a small archipelago.

"Narragansett" is derived from the southern New England Algonquian word Naiaganset meaning "(people) of the small point of land".

Tides in the watershed are measured at Providence, Fall River, Quonset Point, Conimicut Light, Prudence Island, and Newport.

Narragansett Bay circulation is made up of forces provided by the winds, tides, and changes in water density within the watershed.

[7] Tidal mixing is the dominant driver of circulation patterns in the bay, where currents can reach up to 2.5 feet per second.

It has several entrances, however, and historians can only speculate as to the exact route of his voyage and the location where he laid anchor, along with a corresponding uncertainty over which tribe made contact with him.

Around the same time, the Dutch established a trading post approximately 12 miles (20 km) to the southwest which was under the authority of New Amsterdam in New York Bay.

In 1643, Williams traveled to England and was granted a charter for the Colony of Rhode Island and Providence Plantations.

The American victory contributed to the eventual start of the war at the Battles of Lexington and Concord in Massachusetts three years later.

Roger Williams and other early colonists named the islands[15] Prudence, Patience, Hope, Despair, and Hog.

To remember the names, colonial school children often recited the poem: "Patience, Prudence, Hope, and Despair.

[17] Narragansett Bay receives freshwater input from several sources, including rivers (approximately 80%), direct precipitation (13%), wastewater treatment facilities (9%), and unknown amounts from ground-water and combined sewer overflows (CSOs).

Salinity and temperature patterns measured throughout the bay indicate a range of mixed to stratified conditions [18] and the amount of time it takes for the total volume of fresh water in the bay to be equaled by the fresh water input (flushing time) varies from 40 days to 10 days, depending on freshwater input.

This is due to warmer temperatures and higher biological demand for oxygen in the summer and the opposite in the winter.

[21] Annual blooms have shrunk over the last decade (2006 onward) as the amount of nitrogen (an important nutrient) supply to the bay has decreased by more than 50% due to wastewater treatment facilities switching to a new treatment that involves removal of nitrogen [22] Narragansett Bay is the site of one of the world's longest-running plankton surveys, extending from 1957 through the present.

Researchers at the University of Rhode Island’s Graduate School of Oceanography collect samples weekly and the dataset contains 246 different species.