I'm going to have to credit my husband for this ingenious idea for luring our toddler into the tub. He saved some of the light up ice cubes he's been given at music festivals (apparently they are the promo giveaway of the summer) and kept them in the freezer. When it's time for Z's bath, he pulls one out and pops it into the tub for her to play with. Liquid activates the light source, so we turn off the bathroom lights and watch her experiment with the cube.
You can buy light up ice cubes online at places like this or check your local party supply store.
