Deep in the heart of the Southern Alps Aoraki Mount Cook towers high into the sky above a landscape of rock and ice.
It is quite simply breath taking.
And below the great mountain lies one of our best known glaciers - the Tasman Glacier, a slow moving river of ice, the longest and largest of them all, that is shrinking.
The glacier has 13,000 tourists from all over the world clammering for a look.
There is so much ice off the glacier around that getting the boats out is a delicate task.
Once on the water we get to see the icebergs up close.
Bede Ward manages the tourist operation here and as we head down the lake he knows the bigger bergs by name.
Ice over 300 years old that was once part of the Tasman Glacier is now melting away.
“Basically what’s happened here is that the iceberg used to look like that lovely white one over there and it has just rolled over and rebalanced itself there and it exposes its lovely blue ice from underneath,” said Ward.
And if you want to know what the ice inside the Tasman Glacier looks like, well it looks clear and pure, the result of snow that has been compacted down 50 metres a year over three centuries into beautiful ice crystal.
The lake first formed back in 1973 - the Tasman glacier has retreated seven kilometres and is moving back fast.
On the lake most of the icebergs here are a year old, what we see on top of the water is just 10 percent of the iceberg, the other 90% is under water.
So why are so many icebergs carving off the terminal face and falling into the water?
“The water of the lake is warmer than the ice so it is detrimental to the ice eating away at the ice 30cm a day so it's not really helping the cause. Some say it is global warming, some say it is not, but I think humans have had an impact on the ice and the glaciers around the world but time will tell, a lot can happen in 20 years,” said Ward.
Scientists say that the Tasman Glacier could shrink another 11 kilometres up the valley but it won't disappear altogether.
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