Tash-Rabat to Chatyr Kol
This is a great hike from Tash Rabat to Chatyr Kol. It's long, so if you are taking camping equipment, you would probably want to do this in two days. There is a yurt camp at the end of the hike, so you can do this with a day pack. There are yak herds along the trek, so you are likely to encounter them. They tend to be afraid of humans.
Note: On the way down to Chatyr Kul, you will encounter a drop off, where there is a waterfall. The climb from there should not be attempted except by experienced climbers with climbing equipment. When you come to the drop off, if you look to your left, you will see a narrow slot: follow it up, then down, to bypass the waterfall. It may look like it drops off at the end, but it opens up to a walk off.
From Tash Rabat, follow the river up the valley. About half-way up the valley (at about 40º46'37.9”N, 75º18'20.7” E), the river splits—follow the right (westerly) fork. When you come to the end of the valley, you can continue straight up, which is a tough climb; left (where the path is); or right (westerly). Any of these ways will take you to the lake, but you may have a hike to get to a yurt camp. The right (westerly) pass leads straight to a yurt camp. See note above about the waterfall on the way down. If you're camping, the left path is slightly easier. Note that if you take the right path, you won't be able to see the lake from the pass: the climb down bends to the left, at which point the lake will be visible (if there are no clouds).
Distance (one way): 21.6 kilometers
Start: 40º51'47.3”N, 75º16'37.5”E; elevation: 2,978 meters
End: 40º43'10.5”N,75º17'9.44” E; elevation 3,616 meters
Pass: 40º44'23.6”N, 75º17'26.9” E; elevation 3,996 meters
Total elevation gain (one way): 1,338 meters
Total elevation loss (one way): 703 meters
Difficulty: 4 (long, but not too steep, except at the pass. See note about bypassing the waterfall).