The Ruapehu Massif is built of multiple cones. The highest mountain in the North Island, Ruapehu stands at 2797m (9175ft). The last eruptions were in the winters of 1996 and 1995.

Ruapehu has a lake in it's currently active crater about 1km across. On rare occasions with no activity the lake has frozen over, but the temperature easily reaches 60°. Crater Lake introduces it's own danger of lahar's or volcanic mud flows that are created when lake water and volcanic debris are thrown from the crater, flowing down the valleys at speeds of up to 90 km/h.

Ruapehu is a popular winter playground, with 3 ski fields on it's slopes - with several thousand people frolicking in the snow, lahars remain the most serious hazard on Ruapehu.