I've taken to sitting Henry up in the bathtub sans bath-chair in just a few inches of water. He can sit up well enough now that he's free to play and grab at toys without fear of a face-full of water (which thankfully, he's weathered quite well in the past). Tonight after he finished playing with his crab, he began splashing his hand up and down in the water. This caused tiny bubbles to form which absolutely captivated him. He would try to pick the them up with his fingers and then get so excited he'd splash and the whole thing would start again.