Underwater. I don't SCUBA dive or even swim that much, but I love the quiet of being submerged in water.
Utility. I try to avoid objects that have little or no usefulness, but have yet to fully live by William Morris's famous quote: "Have nothing in your house that you do not know to be useful or believe to be beautiful."
Uncles. I have a lot of them.
Unbridled joy. That's what I felt when I tested out my new bike yesterday.