The current rate of discovery of bodies beyond the orbit of Neptune, and of their diversity, is changing our view of the Solar System. Such objects form the Kuiper Belt, a loose disk incorporating the orbits of Pluto and of various other newfound objects out there in the cold. None of the Kuiper Belt objects is large—all are less than 2500 km in diameter so at least 1000 km less wide than Earth’s Moon. However, eight of them have been classified as dwarf planets, and several have moons of their own. What are they like, in close-up? Only Pluto (with Charon) and Arrokoth have been subjected to visits by a spacecraft, the New Horizons mission. Pluto was once thought to be likely to be a cold and inactive place but has turned out to be cold, sure, but amazingly active. Arrokoth is a much smaller object, floating alone in relative darkness, far from the Sun. The others we know less about, but Pluto’s evidence, especially, suggests that there is much richness out in the Kuiper belt, waiting to be explored. And further out, much further, in the Oort cloud, there is more.