Koʻolau Range, Mountain range in Oahu, US.

The Koʻolau Range stretches across eastern Oahu with distinctive steep cliffs that rise sharply from the coast. Three major highways tunnel through the southern section to connect different parts of the island.

The range formed millions of years ago as part of a massive volcano that later experienced catastrophic collapse on its eastern side. A pivotal moment came in 1795 when warriors were forced over the cliffs during battles that unified the islands.

The name Koʻolau means "windward" in Hawaiian, naming the side of Oʻahu that faces the trade winds. The range also carries the memory of the 1795 battle in which Kamehameha I's troops drove Oʻahu's defenders up the Nuʻuanu valley and over the cliffs at Nuʻuanu Pali.

Visit during drier months when visibility is clearer, as higher elevations attract clouds and rain throughout the year. Several trails offer views from different perspectives, so wear proper footwear and check local conditions before heading out.

The debris field from the collapse lies on the ocean floor northeast of Oʻahu, stretching nearly 100 miles (160 km). Kāneʻohe Bay occupies what was once the volcano's summit caldera, so the bay itself marks where the peak stood.