Is very beautiful , but i cant find anything on diving in it. any experience?
BTDT. My advice is, as with most mountain lakes, don't bother unless you just want it for the altitude experience. What you see above water is a lot more interesting and prettier than what's below. I did a 43 minute dive down to 85' there in August of 2008. It was cold (down to 41 deg.) and barren with the expected strong thermocline around 30', and I saw one fish during my safety stop. I entered and exited at the east end by the picnic tables.
Unlike Tahoe there are very few rocks, just occasional dead trees and branches, and the bottom is soft silt instead of sand once you get deeper than 15 feet or so. IIRR I was able to insert my arm up to the shoulder in the bottom with ease, and could probably have kept going if the two hadn't joined. I could see the sun's disk down to 45' or so, and the sunlight down to 65' or thereabouts. It was quite dim at my deepest point, and the vis was surprisingly poor at depth, only 10'-15' IIRR.
Because motor-powered boats aren't allowed here the people who access the lake tend to be a more environmentally-sensitive crowd, so you don't get all the human trash that at least gives you something to do to relieve the boredom in other lakes.
I've dived 4 mountain lakes now, Tahoe, Angora, Tenaya and Convict, and can't say that any of them are worth it for the diving compared to Monterey. But I'll probably dive Saddlebag Lake just outside the park (10,087') sometime, just so I can say I've dived at over 10,000 feet.
If you decide to do it anyway, like Chuck said be aware of the altitude corrections you need to make, and/or use nitrox if you can. At Tenaya I think I used 36%, which pretty much got me back to my original sea Level air NDLs, albeit you're still depth limited by the Nitrox.
Guy