The Pink and White Terraces on Lake Rotomahana are thought to have been the largest silica sinter terraces on earth.
Considered to be the eighth Natural Wonder of the World, they attracted visitors from far and wide to marvel in their beauty and to bathe in the mineral-rich geothermal waters.
The terraces were formed as silica-rich water flowed from natural hot springs and geysers on the lake’s edge. As the water cooled, the silica crystallised, creating the terraces and pool-like structures stepping down toward the lake as water flowed over the edges of each layer above.
The larger White Terrace, Te Tarata (“the tattooed rock”) tumbled to the lake from a height of 30 metres, fanning out to a width of around 240 metres at the bottom. The Pink Terrace, or Te Ōtūkapuarangi (“the fountain of the clouded sky”), was slightly lower and smaller, getting its pink colouration from sulphides in the water.
Visiting the terraces became New Zealand’s first tourist activity, and a tourist hub was created at the village of Te Wairoa. Māori guides from the local tribes paved the way for the future of tourism in New Zealand, a tradition continued to this day with many of their descendants still guiding visitors in the Rotorua region.
On June 10 1886, a huge eruption ripped open the summit of Mount Tarawera, creating a rift 17km long. A hydro eruption blasted Lake Rotomahana to 20 times its original size. The surrounding area was covered in layer upon layer of rock, mud and ash, burying villages, including Te Wairoa, and extinguishing all plant and wildlife. The Pink and White Terraces were presumed to have been destroyed and lost forever.
Over the next few years, the craters from the eruption filled with water and Lake Rotomahana became the much larger lake as we know it today, with water levels 60 metres higher than the original lake.
However, there remained much intrigue about the terraces.
Studies to investigate the geothermal systems and map the lake floor uncovered shapes thought to be remnants of the terraces. Cornel de Ronde from GNS Science lead a joint New Zealand-United States project team to send two automated submarines into the depths of Lake Rotomahana. They discovered structures they believed to be part of the original Pink Terrace 60 meters beneath the lake’s surface.
Further studies appeared to support these findings until an archaeological study by Rex Bunn suggested a different location for the terraces, reverse-engineering original 19th century surveys by geologist Dr Ferdinand von Hochstetter. These claims prompted further investigation and imaging by De Ronde and his team, concluding that they still believe the terraces to be in their original position.
This technology and research was used to create the Waimangu App, an augmented reality guide to the Waimangu Volcanic Valley and Lake Rotomahana. Using this app on the Lake Rotomahana boat cruise, you can see the terraces in augmented reality in their actual location.
As the research continues, the next step is to use a manned submarine from Germany to dive into the depths of the lake, allowing an up-close view to film and further investigate the familiar terrace shapes.