Snow patterns beside Blue Lake, Mt Tongariro, Tongariro National Park

Mt Tongariro, the volcanic massif that gives Tongariro National Park its name, is made up of numerous volcanic vents of varying ages. These days, Red Crater is the most active part of Mt Tongariro, steaming away in the central part of the massif between Central Crater and so-called South Crater (which is actually erosional in origin and not a true volcanic crater).

The circular Blue Lake occupies an older explosion crater on the northern side of the Tongariro massif, at an altitude of about 1700 metres. The lake regularly freezes over in winter, and, after particularly heavy snowfalls, it can be difficult to distinguish where the lake edge actually lies – making for an interesting exercise when choosing a suitable tent site for the night.

This photograph was taken on the eastern margin of the lake, a narrow, almost-flat ‘beach’ of fine scoria that has been shaped into parallel ridges by wind-whipped waves during westerly storms. A light snowfall had fallen the day before, and the gradual thaw that followed resulted in these striking patterns of melting snow separated by ridges of bare gravel.