The Bay Area is an awesome place for triathlon: perfect weather year-round, biker-friendly roads (flat, hilly: take your pick), runner-friendly trails. But it doesn’t have very many open-water swim options.
[And no, the cold Pacific is not a viable open-water swim option, if you ask me.]
There are plenty of lakes nearby, but many of them do not allow swimming outside of organized events (boo, UVAS!). One notable exception is Lake Del Valle in Livermore, so this weekend we headed out there — an hour-plus drive — for a morning of swim-bike-run fun. 
We got there early (8 a.m., don’t ask me when I got up), so we could beat the crowds: a great idea, it turns out, because later in the morning the water got quite busy with boats.
I can’t stress enough the importance of practicing open-water swimming if you’re new to triathlon (like me). My first such swim – in a wetsuit, and not counting swimming in the Black Sea growing up – was during my first triathlon and I certainly wish I’d practiced at least once before. No amount of swimming in a pool will prepare you for open water, it’s just that different.
Sighting, in particular (looking ahead of you every so often to make sure you’re swimming the right way), completely throws me off rhythm and I cheated quite a bit: breaststroke, oh yea. 
(And yes, I didn’t wear a wetsuit. The water was great!)
I tried my new Garmin in an open-water swim for the first time, too:
[Thanks for the photos, Julie!]
We swam 0.6 miles, according to my watch, though looking at the GPS route, I kind of doubt its accuracy very much.
Looks like it was losing GPS signal every now and then and jumping around in the water, because what we did was basically four out-and-backs to a nearby buoy:
My guess is, the signal will be more consistent if I stick the watch under my swim cap. Smarter, if I want more accurate data — not so smart if I somehow lose the watch in the water.
The bike leg was quick, but pretty challenging. If you go out there to bike, be ready for the massive hills going out of the park. We only did 8.75 miles, but the total climb was 1231 ft. Wowza. 
The run was my favorite part, obviously. (I’m getting the impression that most people in triathlon hate the run. I don’t get it? I spend the entire swim and bike looking forward to it?)
We decided to forego the monster hill and headed in the opposite direction, up a dirt path around the lake. Such a beautiful place to run! 
That road was just shy of a 15-min run at an easy 9:30 pace for me (not sure what that makes it, 1.6 miles each way?), so I ran a mile out and back, then again out to the end of the path and back, for a total of five miles:
Just one semi-tough climb, rewarding you with a great view from the top of course (see the photo at the very top of this post).
Totally worth it to go to the very end of the path, too:
If you’re looking for a place to practice open-water swimming and do some bike-running afterwards, Lake Del Valle is definitely a great way to go — even if, for me at least, it was definitely out of the way!
What is your experience with open-water swimming? Like? Not like? Never!?!?
I don’t know if you still read this, but can you swim at Del Valle in places other than the beaches?
I’m not sure, to be honest. The only time I swam there was the one documented on here… The Parks website may have more information?