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The couple attempted to reach the summit of 6800m Anidesha Chuli.
The experience of attempting to reach the top of the unclimbed peak - also known as the White Wave - was a ''really cool experience'', despite only reaching a height of about 5700m because of dangerous conditions, Mr Hersey said.
''There's a whole range of things that you don't get at home and that's before you even get to the climb,'' he said.
The couple trekked for 10 days from Kathmandu, Nepal, to their base camp at 5000m and spent the next three weeks on the mountain.
They returned to Dunedin on Tuesday and were disappointed to find the weather colder than Nepal's.
Mrs Hersey said they were ''certainly disappointed'' not to reach the summit.
''But given the conditions, it was a fairly clear-cut decision and the whole experience was really rewarding in itself.''
Her husband was struck by acute mountain sickness and had to return to base camp.
Their climbing partner, Australian John Price, also became extremely sick during their hike to base camp.
''Expeditions take all of your mental and physical fortitude and application,'' Mr Hersey said.
''They are certainly about attrition.''
Mrs Hersey and Mr Price pushed for the summit without Mr Hersey, because of his sickness, but found themselves ploughing through deep snow.
''It was really unconsolidated, which means not only are you ploughing through snow, but you take one or two steps and then you are up to thigh-height snow and then you take one or two more steps and you are up to chest-height,'' she said.
''You can easily break a leg in those conditions.''
While the disappointment of not reaching the summit meant the couple ''second-guessed'' themselves, getting home alive was more important than getting to the top of Anidesha Chuli, he said.
''You have only got so much energy living at that sort of altitude,'' he said.
''Your body basically eats itself.''
The couple were already planning their next ''project''.
''There's heaps of new stuff to be done in New Zealand,'' Mrs Hersey said.
''Not in terms of new summits, but new routes.''
''And we haven't climbed in China or South America yet,'' Mr Hersey added.
But the couple's immediate plans were to finish unpacking.