Blue Lake (Otago)

Blue Lake (Māori: Rota Kahurangi) is a small lake located in Nelson Lakes National Park in the northern reaches of the Southern Alps of New Zealand's South Island. It is renowned for having the clearest natural fresh water in the world.

The lake is situated in a glacial valley to the west of the Travers Range and is fed by runoff from the surrounding mountains. The water then flows out into the Sabine River. Its exceptional clarity stems from its glacial origin, filtering of water through landslide debris that forms the lake's bed, and the absence of algae. Scientists have measured underwater visibility of up to 80 meters (260 ft).

The lake holds significant cultural importance for the local Māori iwi, Ngāti Apa ki te Rā Tō, who consider it a taonga, or treasure. The name Rota Kahurangi translates to "Lake of Great Value." Access to the lake is restricted to protect its pristine condition and respect its cultural significance. While tramping in the region is permitted, direct access to Blue Lake is generally discouraged.