Peninsulas are land formations, while bays are bodies of water. However, the two geographic features often occur side by side. Peninsulas are areas of land that are surrounded by water on three of its four sides. Bays are bodies of water that are surrounded by land on most sides.
Peninsulas may be very large or very small. Very small ones may not show up on maps, while very large ones are important geographic features. For example, Florida is an example of a large peninsula. Other notable peninsulas include Italy, Baja California and the Korean Peninsula.
Some geographers use the terms "bay" and "gulf" interchangeably. While bays are usually smaller than gulfs, the Persian Gulf is much smaller than Chesapeake Bay. Usually bays form as outgrowths of an ocean or sea, and they usually have a relatively wide mouth. Gulfs, by contrast, usually have a very narrow mouth that connects to the larger ocean. The Gulf of Mexico is a good example of a typical gulf, while Hudson Bay’s large mouth provides a good example of a bay.
The world’s largest bay is the Bay of Bengal, which was formed when the Indian subcontinent crashed into Asia. The world’s largest peninsula is the Arabian Peninsula, which contains six countries.