The Southern Alps run along nearly the entire length of New Zealand’s South Island. They are a tectonically active range, rising rapidly due to the collision of major plates. Geographically, they create a significant rain-shadow effect; the western slopes receive extremely high rainfall and host temperate rainforests, while the eastern Canterbury Plains are much drier. This range is structurally distinct from the European Alps but shares similar glaciated landforms. They are essential to New Zealand’s geography, acting as a drainage divide and providing the snowmelt that fuels the nation’s hydroelectric power schemes.