The Emerald Lakes are three small crater lakes on the Tongariro Crossing in Tongariro National Park. In Māori they are called Ngā Rotopounamu, meaning greenstone-hued lakes. The website says they are one of the top attractions on the Tongariro Crossing hike. The lakes formed as water filled craters left by volcanic explosions near the peak of Mount Tongariro. Their colour comes from minerals in the surrounding landscape that dissolve in the water. Walkers see the lakes come into view as they start to descend from the highest point on the trail, and the Emerald Lakes Lookout on the trail gives views of all three.
The colour is most vivid on sunny days, and the website suggests summer and the shoulder months as the best time to see them, when there may be a dusting of snow around the lakes. In winter, snow usually covers the landscape and the lakes may not be visible. Swimming is not advised, because the water is ice cold and the area is geothermal, so the lakes are best admired from a safe distance. A Ketetahi car park shuttle takes walkers from the end of the track back to the start point. Our pick in National Park for a clear summer day on the Crossing.