Silica Rapid is a short walk, readily accessible to frontcountry trampers. The supernatural shades of these rapids result from volcanic minerals that abound in Tongariro National Park, Aotearoa’s oldest national park with World Heritage status. We started at Bruce Road with its uphill undulations, knocking off a wintry, exposed section through tussock for the first half hour. It was cold and wet. I was glad to be waterproofed all over. Silica Rapids is extremely colourful. Turmeric-coloured rocks shine under a clear mountain stream. Their unusual colour is due to the volcanic minerals of Tongariro National Park. Apparently, a spring just…