Mount Ruapehu, Active stratovolcano in Tongariro National Park, New Zealand.

Mount Ruapehu is an active stratovolcano at the southern end of the Taupō Volcanic Zone, inside Tongariro National Park. Its broad summit ridge carries three peaks — Tahurangi (2,797 m), Te Heuheu (2,755 m) and Paretetaitonga (2,751 m) — with the warm, acidic Crater Lake between them. Dark grey-brown rock and scree are streaked with snow patches, and forest covers the lower slopes.

A lahar from the volcano destroyed the Tangiwai railway bridge on Christmas Eve 1953 and killed 151 people on a moving train. The disaster remains one of the worst rail accidents in the country's history.

The name Ruapehu comes from Māori and is usually translated as "pit of noise" or "exploding pit", referring to the volcano's active crater. The crater lake is called Te Wai ā-moe in Māori. The mountain lies within Tongariro National Park, and its upper slopes appear in the film adaptation of The Lord of the Rings as Mordor.

Two ski resorts on the slopes offer winter sports options from June through October for visitors of all experience levels. Access roads are well maintained but require winter equipment during snow conditions.

The mountain carries eighteen glaciers, including New Zealand's only crater glaciers with ice layers reaching 130 meters deep. These ice masses sit directly beside the active volcanic crater and form a rare geological combination.