I spent the long weekend camping at middle Young Lakes, and hiked to the Mt. Conness summit platform Sunday. I didn't like the exposure to continue to the top, but the pink chicken's advice about the summit platform was correct - it's a great place to explore.
The swimming in the middle lake was pretty good - a little gooey stuff on the bottom but not too bad, and I enjoyed the water temperature.
Morning view of the middle lake:
Sunset view, middle lake:
The upper lake:
View of the middle and lower lakes:
The meadow/water leading towards Mt. Conness:
Conness Lakes and the 20 Lakes Basin:
Southwest view from Conness. The lower lake is in the foreground. You can see Tenaya Lake in the background, with Clouds Rest to its left, and Half Dome beyond.
The east side of Mt. Conness, with the glacier to the bottom:
View towards the White Mountains:
Upper Young Lake, and in the background the Cathedral Range: