Chesapeake Bay is an estuary, where fresh water from rivers mixes with saltwater from the ocean.

Chesapeake Bay is one of the largest estuaries in the U.S. It is formed where the Chesapeake Bay watershed's rivers meet the Atlantic Ocean's saltwater, creating a mix of freshwater and saltwater. Estuaries like Chesapeake Bay are incredibly productive ecosystems, providing habitat for various species, including fish, birds, and invertebrates. While it does have wetlands along its shorelines, it is primarily known for being an estuary, not a coral reef or mangrove forest.