I have often taught about total internal reflection and explained that if you were underwater in a swimming pool, you would be able to see the pool floor reflected by the water surface above you. I've never been able to photograph it because my camera isn't waterproof. So here's TIR at Matryport Aquarium. I was surprised because the whole surface seemed to act like a mirror. If you are underwater in a pool and look straight above you, in theory there shouldn't be TIR because the light doesn't bend. That didn't seem to be the case no matter how close I put my head to the glass. Maybe that was due to refraction in the glass. The glass walls of the tank seemed weird.
