You get air lifted onto the glacier by helicopter and then walk for 2 1/2 hours before being lifted off again. The walk includes getting to grips with walking on crampons, exploring ice caves, crevasses and generally being in awe of your surroundings. A fantastic trip and only one company runs hikes up there meaning that we spent 2 1/2 hours on a major tourist attraction and there were only 6 of us there, surrounded by miles of ice. Fantastic.
Updates
Just be prepared for the weather - it rains a LOT on the west coast of UnZed. It is one of the few pieces of land in the Roaring Forties, so you will appreciate the effect of "orographic lifting". Having said that, the west coast of the South Island is spectacular, with pristine wilderness and deeply eroded, waterfall laden, valleys.
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