On Thursday, Sarah got the bus south and Pip met her at National Park. (This is the name of the little settlement, which is basically back-packers and ski-lodges.) We drove back up towards Whakapapa, and spent the night at the Mangahuia DOC site (Pip's second night there.) The next day we walked up the river. On the way, we crossed what are known as the Golden Rapids, where the water is stained brown and yellow (gold in the right angle of sunlight) with iron oxide off the mountains.
Climbing above the tree line into alpine bog takes you towards these amazing rapids. The white aluminium-silicate clay is washed down from the peaks, where the silica is created by the heat of the volcanic action. Where the water runs fast, it becomes aerated and the minerals 'fall' out of it to be deposited in these blinding shelves.