on most sides by water.

A peninsula may be bordered by more than one body of water, and the body of water need not be an ocean or a sea. A piece of land on a very tight river bend, or one between two rivers, is sometimes said to form a peninsula, for example in the New Barbadoes Neck in New Jersey, United States. The connection between a peninsula and the mainland may be an isthmus; for example, the Isthmus of Corinth