Mt Ruapehu and theWhangaehu River. Scene of the Tangiwai disaster wherein sudden surge of mud-laden water (a lahar) – swept down the river, significantly weakening the structure of a railway bridge at the small settlement of Tangiwai.

The overnight express train between Wellington and Auckland passed over the bridge minutes later, causing it to collapse into the turbulent waters.
Of the 285 people on the train, 151 were killed.