Land juts out into the water and is surrounded on three sides. A peninsula is that projection of land. The Iberian, Italian, and Korean peninsulas are familiar examples; smaller peninsulas appear along many coastlines.

Peninsulas often have climates moderated by the surrounding water and have historically been attractive for settlement and defense. Their shape can create distinct cultural or political identities. Access is usually easiest from the landward side, which can become a strategic corridor or chokepoint.

Rising sea level threatens low-lying peninsulas with inundation and erosion. Geographers study their formation through processes of deposition, erosion, and tectonic uplift. The three-sided embrace of water remains the defining geometric trait.

• Land surrounded by water on three sides
• Connected to a larger landmass
• Often climatically moderated by water
• Historically strategic for settlement