Narragansett Bay is the largest estuary in New England. It is made up of three interconnected passages that run north to south: the West Passage, the East Passage, and the Sakonnet River. These passages are actually ancient river valleys that were inundated by sea water:
- West Passage - separates Conanicut Island from the mainland on the west and has an average depth of 33 feet
- East Passage - separates Conanicut Island from Aquidneck Island and is deep enough for large ships with an average depth of 44 feet
- Sakonnet River - separates Aquidneck Island from the mainland on the east. The northern end is known as Mount Hope Bay.
