Part of Italy is a peninsula, and it's a pretty famous one, because it looks like a boot. A peninsula juts into the water but has at least a narrow a connection to land. If the boot broke off from Italy just below the "knee," it would be an island.
The word peninsula, which entered English in the 16th century, comes from the Latin words paene, "almost," and insula, "island." Some confuse an island with a peninsula because both are surrounded by so much water, but a peninsula is connected to a mainland at some point, while an island is completely encircled by water. In most cases, a peninsula is narrow and long, resembling an arm or leg.