A peninsula (Latin: paenīnsula, "paene-": almost + "īnsula": island; also called a byland or biland) is a piece of land that is bordered by water on three sides but connected to mainland. In many Germanic and Celtic languages and also in Baltic, Slavic, Hungarian and Chinese, peninsulas are called "half-islands". A peninsula can also be a headland (head), cape, island promontory, bill, point, or spit. Note that a point is generally considered a tapering piece of land projecting into a body of water that is less prominent than a cape. In English, the plural of peninsula is peninsulas or, less commonly, peninsulae.

The Balkans is a peninsula including Albania, Bosnia and Herzegovina, Bulgaria, Croatia, Greece, Kosovo, Macedonia, Montenegro, Romania, Serbia, Slovenia and the European part of Turkey.

Encompassing continental Spain and Portugal, Andorra, British overseas territory of Gibraltar and a small amount of southern France.

Encompassing present-day Sweden, Norway, and part of Finland.

The whole land mass encompassing North and South Korea is a peninsula, surrounded by the Dong Hae (aka. Sea of Japan) on the east, the Nam Hae (aka. East China Sea) to the south, and the Hwang Hae (aka. Yellow Sea) to the west, the Korea Strait connecting the first two bodies of water.