When a range of mountains can be measured tens to hundreds kilometers in length as well width and is located near an active tectonic plate boundary or coast, it called coastal mountain range.

Coastal mountain ranges are typically found along convergent plate boundaries, where two tectonic plates collide. As one plate subducts beneath the other, it can cause the crust to thicken and uplift, forming mountains. Coastal mountain ranges are often associated with earthquakes and volcanic activity, as well as with steep slopes and rugged terrain. Some examples of coastal mountain ranges include the Andes Mountains in South America, the Sierra Nevada Mountains in California, and the Olympic Mountains in Washington State.