Fox Glacier descends from 2,600 metres in the Southern Alps to roughly 300 metres above sea level, ending in temperate rainforest — one of the few glaciers on earth that terminates among tree ferns and rātā. The Māori name is Te Moeka o Tuawe, the bed of Tuawe, after a young man who fell to his death while travelling the ice. The European name honours Sir William Fox, Premier of New Zealand, who visited in 1872. Both names remain in use, and both are carried by guides on a fox glacier heli hike tour today. The glacier is fed by four alpine névés draining a catchment of about 36 square kilometres. Snow compacts into ice at the head, then flows down a valley so steep that the ice moves several times faster than most glaciers of comparable size — historically metres per day during surge phases. That speed is what fractures the surface into the seracs, pinnacles and blue crevasse walls that guided parties now walk between. It also makes the ice unstable enough that access changed permanently. Until the mid-2010s, walkers reached the ice on foot up the Fox River valley. Rockfall and retreat closed that route. Since then, helicopter landings have been the only practical way onto the glacier's mid-section, and the modern heli hike was born of geological necessity rather than luxury. Aircraft lift from the valley floor, cross the terminal face and the moraine walls, and set down on a bench of firm ice well above the debris zone. The surrounding landscape is a UNESCO World Heritage area, Te Wāhipounamu, taking in Aoraki / Mount Cook and Westland Tai Poutini National Park. From the air, the twin glacier route links Fox with Franz Josef, twelve minutes apart by rotor, both draining the same divide. Snow landings on the upper névé sit in a bowl ringed by peaks above 3,000 metres. The glacier has been measured since 1894, and its record of advance and retreat is among the most closely studied in the Southern Hemisphere. It advanced dramatically through the 1980s and 1990s, then entered sustained retreat. Guides trace the old terminal positions on the valley walls as a matter of routine on a fox glacier heli hike tour tour, and the retreat lines are legible from the passenger window. Operations run from 44 Main Road, Fox Glacier, in a village of fewer than 400 residents.