El Calafate is a pleasant enough town (buildings in main street follow wooden alpine style and sell warm clothes and chocolate) built on the edge of the southern end of this national park (and tourism to the park) which contains the largest ice cap outside of Antarctica and Greenland and feeds 48 big glaciers.
Basically the reason that Patagonia to the east is so dry is that all the moisture from the Pacific is trapped in these mountains as ice.
Perito Moreno is one of the 48 that we can all visit without any difficulty and walk on if prepared to don crampons (and be under the age of 45!) It is 250 square kms of ice, over 30 kms in length with a leading edge 5 kms wide and in places 100 metres high - you can take the boat to within about 200 metres of that leading edge...
or stand on one of the viewing gangways at about 70 metres distance.
Why are glaciers blue? - another geeky factoid - same reason water is blue, the more pure the ice (less air) then the more it absorbs the red end of the light spectrum, so when you look down a crevice or sink hole on the glacier, the deeper you can see the more the ice has been compressed the less air there is, the less red the more blue.
All this means for many more expletives of incredibly amazing wondrous humbleness at the sights and sounds of the forces of nature - this immense wonder is truly truly spectacular, especially when bits break off...
We also did one of the tours onto the ice which meant trekking with crampons for an hour and a half or so and then drinking a whisky on glacial rocks :)
walking on ice and to finish off