They told us Perito Moreno Glacier is the fastes moving glacier in the world. I have seen about 10 different glaciers on my jurneys and this one was the only one where I saw falling parts down into the water. It is not looking like it but the front of glacier is about 70 metres height (above water level) and almost 1 km long (just part on this picture).
This glacier is dividing Lago Argentino into two smaller lakes. The output of water is only on the right side co once in few years when water level on left side arise enught, it make a hole in glacie, tunnel where water goes from the left side to the right side. You can see it on [link]