In 1912 a powerful earthquake pushed the Fann Mountains from inside and broke into pieces the southern slope of the Western Fann Range. A river was blocked and an inimitably beautiful lake, Big Allo, appeared. The reservoir in the form of a bean lying in a depression surrounded with huge vertical walls at an elevation of 3,150 m (39°12"27.99"С; 68° 7"52.55"В) is filled with incredibly deep blue ice-cold water. The northern shore features individual relict junipers with strangely twisted and bent trunks, which inevitably attract photographers and those who like unusually shaped wildlife forms.
In the far end of the lake there is a natural dam of giant rocks. The Zindon River can be seen appearing from under the dam only 5 kilometres below the lake. Only from there a broad path leading to the Sarymata Valley begins.
There is another lake, Upper Allo, 2.5 km from Big Allo, upstream along the Western Zindon Gorge, situated at an elevation of 3,380 m above sea level (39°11"5.91"С; 68° 8"39.67"В). The lake is small but also very beautiful in its own way.
Lake Big Allo is a starting point for a number of ascent routes, such as those to Maria (4,790 m), Mirali (5,106 m), Chimtarga (5,489 m), Zindon (4,800 m), Rocky Wall (4,800 m), Blok (4,500 m), Moscow (5,046 m) and Amshut (4,840 m) Peaks.
The most popular tourist route runs across the Chimtarga Pass to Big Allo, with a day’s walk to Upper Allo, and then all the long way down the Zindon and Amshut Gorges to the Sarymat River. Thence you can either walk down to the unique mountain village of Zimtut or trek across the Tavasang Pass (3,307 m) to Marguzor Lakes.
In some water-abundant years tourists can enjoy Lake Little Allo (39°11"55.80"С; 68° 4"24.36"В), which forms in the Zindon Gorge at an elevation of 2,340 m. Filtering through the 5-kilometre Big Allo dam, in Little Allo the water turns crystal clear and unusual greenish colour.