An island is a special piece of land that has water all the way around it. Imagine a little patch of land sitting right in the middle of a big, blue ocean or a quiet lake. You would need a boat or a plane to visit one! Some islands are tiny with just a few trees, while others are big enough for many people to live on.
A peninsula is land that is almost surrounded by water, but not quite! It has water on three sides, but one side is still connected to the main land. It looks a bit like a long finger pointing out into the sea. Because it is still attached to the land, you can drive a car or ride a bike to get there. Florida is a very famous peninsula that you can find on a map!