Big Almaty Lake is set high up in gorge of the Bolshaya Almatinka river, 2,511 meters above sea level and 28.5 km south of Almaty. It lies in a hollow like a gleaming mirror, surrounded on all sides by majestic peaks. Nearly all of the mountain lakes in Tien-Shan are the results of earthquakes, and Big Almaty Lake is the largest of these. Three main peaks tower above the lake and can be seen from the northern end of the dam: Sovetov (4,317 m) to the south-east, Ozyorny (4,110m) to the south, further up the river valley, and the forested slopes of Turist (3,954m) to the south-west. West of Turist is the crest of Bolshoi Almaty Peak, a 3,681-m-high pyramid which is visible from the city centre. The lake changes color from light green to turquoise depending on the season. Fed by glacier water, the lake is 1.6 km long, almost a kilometer wide and 40m deep. Higher up above the pale blue chalice of the lake is the domed Tien-Shan Astronomical Observatory, in a very ancient glacier valley 2 km from the lake and at an altitude of 2,700m. Walk another 8km and you will reach the CosmicRays Reseach Station at 3,300m, near the Zhosylkezen Pass. You can camp here for the night and gaze up the stars. The path forks after the dam at Big Almaty Lake, leading to many places that are perfect for hiking, skiing, bird watching, picnicking or camping. The left-hand trail goes east to the Turist Pass and Left Talgar valley, while the right-hand path crosses the river and climb to the Ozyorny Pass. The Ozyorny and Prohodnoi Gorges stretch out like two ample sleeves of the Big Almaty Gorge, each beautiful and surprisingly different from the other. From the Almaty-Alagir Pass there is a starting point for routes to Lake Issyk-Kul (in Kirgystan) of varying length and complexity – the Ozyorny, Aksu, Prokhodnoi and Kok-Kairyk Passes. The season for trekking to Issyk-Kul is late July to August. Zhasyl-Kol, a moraine lake of heavenly beauty (3,000m), nestles between the Zaili Alatau and Kungei Alatau mountain ranges. The Prokhodnoi Gorge has a spacious, picturesque valley that brings together all the diverse colors of the mountains. The Alma-Arasan Gorge, with its graceful little waterfalls and hot springs, is always popular for adventure holidays.