Big Almaty Lake (BAL) several names like Bolshoye Almatinskoye and Bolshoye Almatinskoye Ozero (Big Lake of Almaty in Russian or BAO) and Zhasylkol (Green Lake in Kazakh).
It isn't that big as it's called. It's only 1,6 km long, just under 1 km wide and up to 38 m deep. It is surrounded by three mountain peaks: Soviet (4 317m), Ozerniy (4 110m) and Tourist (3 954m).
Depending on time of day, month or year, BAL changes its colors and reflects the surrounding beauty on its surface. When you are in Almaty and you've had enough of the city bustle, I recommend you head towards BAL for a bit of fresh air and tranquility. It's only about 25 km from the city and sits about 2500 m above sea level.
You can get there On Foot. I suggest to:
By 4WD (however you do see some chancers on normal cars as well, I personally don't recommend):
September colors of Almaty Lake
(all pictures are courtesy of Malene Heine, unless otherwise indicated below any picture)
October colors of Almaty Lake
Image credit to Rise2Rise
November colors of Almaty Lake
Want to know what's further up like the hikers below do? It's not a secret. About 2 km further up on a very ancient glacier valley you can find the Tian Shan Astronomic Observatory (2 700m above sea level).
If you keep going past the observatory after about 8 km you hit the Cosmostation (Station for Researches of Cosmic Rays) and you find yourself at 3 300m above sea level.
You can even cross the border to the Kyrgyz Republic, provided all your papers are in order, situation is stable in the country and the borders are open.