About the age of 11 months, our DS went off his bath, which he previously enjoyed. He just stands in it yelling; won't sit down, even with company. At first we thought it was because he didn't want to be enclosed (as he was just starting to walk), but he doesn't mind standing in the bath to be showered!
I'm not overly bothered, as showering is quicker and greener, but am curious if any other MNer has experienced the same thing, and has any theories on the subject.
Oh, and he's happy enough in a swimming pool too, so it's not water per se.