Gangapurna Lake (3,540m) is a glacial lake at the foot of the Gangapurna glacier, a one-hour walk above Manang on the Annapurna Circuit. The lake's colour changes through the day from milky turquoise to deep green depending on the light, fed by glacial melt from the ice face above. It is the classic acclimatisation walk from Manang — easy enough to do in the morning before the afternoon winds pick up, and high enough to give a useful altitude boost before the next day's climb.
From the lake shore, the ice cliffs of the Gangapurna glacier are directly above and the peaks of the main Annapurna range fill the skyline to the south. The silence of the place, after the noise of the Manang teahouses, is striking. A few prayer flags mark the shore; otherwise there is nothing human here except the trail.
The more committed acclimatisation option is to continue from the lake up to Ice Lake (4,620m), a further two to three hours of steep climbing above the Gangapurna lake. Ice Lake gives excellent altitude preparation for Thorong La and views north across the Tibetan plateau. The round trip from Manang to Ice Lake takes five to seven hours.