Estuaries An estuary is a coastal area where fresh water from rivers and streams mixes with salt water from the ocean. Many bays, sounds, and lagoons along coasts are estuaries. Portions of rivers and streams connected to estuaries are also considered part of the estuary. The land area from which fresh water drains into the estuary is its watershed. Estuaries come in all shapes and sizes, each unique to their location and climate. Bays, sounds, marshes, swamps, inlets, and sloughs are all examples of estuaries. An estuary is a fascinating place from the largest landscape features to the smallest microscopic organisms. When viewing an estuary from the air on is practically amazed