A peninsula is a piece of land that extends into water and is surrounded by water on most sides, while still connected to a larger landmass.
Examples of peninsula shape
A peninsula can be narrow or broad. It may extend into an ocean, sea, lake, or river. The defining feature is that it remains attached to land.
Peninsula versus island
An island is surrounded by water on all sides. A peninsula is only mostly surrounded, so it still has a land connection.
A peninsula is a useful geography term for understanding coastlines and map shapes.