Bay

A bay is a part of the sea, ocean, or, in some cases, a large lake that extends into the land and is partly enclosed by the surrounding coast. Its opening is often wide, but there is no universal rule that precisely separates a bay from a gulf. Bays can form in several ways.

Waves and currents may gradually erode softer rocks along a coast, while harder rocks resist erosion and remain as headlands. Other bays form when rising sea levels flood river valleys or low-lying coastal areas. Glacial erosion can also create broad coastal valleys that are later flooded by the sea.

Because many bays are partly sheltered from waves coming from the open sea, their waters can be relatively calm. This makes some bays suitable for ports, fishing, aquaculture, recreation, and coastal settlements, although conditions vary considerably. Their shape, depth, tides, currents, and sediment supply influence the ecosystems found there.

Depending on local conditions, a bay may contain beaches, mudflats, marshes, seagrass meadows, or rocky shores. Some bays are small and shallow, while others cover hundreds or thousands of square kilometers. The Bay of Bengal, the Bay of Biscay, and Hudson Bay illustrate the diversity of these coastal forms. The term “bay” therefore describes a broad coastal feature rather than one specific geological type.