In the comments, jmjmartin commented:
My cat used to jump into the bath, she would play for ages with the water on a trickle.
One day, I'd ran a bath, and was shaving in the basin, when I heard the cat running towards the bath, I shouted 'NO'... Too late! SPLASH...lol.
After that she still got in the bath, but stood on tiptoes & looked over the edge first to make sure it was empty...