It's amazing how quickly young children can learn to swim. My daughter went from disliking the water to swimming 200m with perfect technique within a couple years.
Learning to tumble made me laugh, but is a good idea :)
Learning to fall is a hugely beneficial asset. It's how skateboarders are able to get up, over and over. First thing you learn is how to fall properly, without seriously injuring yourself. It will happen, but being able to roll away, or bail correctly is essential.