Emerald Lakes

BY JULIAN THOMSON (OUT THERE LEARNING)
Accessibility: DIFFICULT
Emerald Lakes, Tongariro, Julian Thomson / GNS Science
There are several explosion craters at the foot of red crater, three of which are water filled to form the lakes.
Emerald Lakes, Tongariro, Julian Thomson / GNS Science
These picturesque lakes and associated hollows next to Red Crater are a small chain of explosion craters that were formed within the last 1800 years. They were produced by gas and steam eruptions that scattered small yellow / grey lapilli (defined as erupted rock fragments or tephra ranging from 2 to 64mm in diameter). Areas of warm ground and fumeroles are associated with these lakes and Red Crater. These are related to the underground hydrothermal system that is heated by magma at depth. The lakes are acidic, with a pH of between 3 and 5. The green colour arises from sulphur entering the lakes from below. The lakes were originally named Rotopounamu meaning ‘greenstone lake’.
Emerald Lakes, Tongariro, Julian Thomson / GNS Science
It is interesting to explore the area around the Emerald Lakes if you have the time. How many explosion craters can you identify in total (including those without water in)? Look for the lapilli deposits around the craters and the steaming ground more on the eastern side. The colours of the rocks and lakes make for great photography here.
Directions/Advisory

At the midway point of the Tongariro Crossing, Accessed from Mangatepopo Car Park (as per Red Crater) or from the Ketetahi road end on State Highway 46 / Lake Rotoaira Road.

All waterways including the lakes on Tongariro and his peaks Ngauruhoe and Ruapehu are sacred to local iwi, Ngāti Hikairo ki Tongariro. Kaumātua Te Ngaehe Wanikau asks visitors to the area to respect the sanctity of the maunga tapu (sacred mountains) by not touching or entering any of the waterways including the alpine lakes. Ngāti Hikairo ki Tongariro places extreme importance on their guardian role in protecting Tongariro and his peaks.

Google Directions

Click here for Google driving directions

Accessibility: DIFFICULT

Follow the Tongariro Crossing track for three or more hours from either end. The lakes are right next to the track near the turn off to the Oturere Valley.

Features
Volcanic Geothermal
Geological Age
Recent, formed in the last 1800 years.
Zealandia Evolution Sequence
Pākihi Supergoup: 5 million years ago – present