Yeah, I have to definitely up my water drinking. (I'm just finishing off my first liter of the day right now.) Cool thing was that my first cramp showed up just as I was finishing the last few strokes of my last lap!! So, I think it might have been more of a "get my legs used to doing 33 laps" thing than a deficiency thing. But, I am definitely going to continue drinking more water and getting my vitamins in ahead of time.
At the end of the swim, the woman swimming in the lane next to me and I had a little chat. She looks like a great swimmer, but was saying how her daughter swims a mile in 18 minutes, so when she comes home boasting that she can get her mile in an hour, her daughter laughs at her. But, considering that her daughter just taught her how to swim three years ago, I thought she was doing amazingly well and told her so! When she said that she had been terrified of the water before then, I was flabbergasted because she's so good now.
My mom was in a similar situation, learning how to swim for the first time in her 40s, but she never got past the stage of "dog-paddle and can keep her face under the water for five seconds only." I'm proud of her for getting that far, actually, considering that she's still rather afraid of the water.