Watershed takes a look at the more distant future. A very long time after the beginning of the Pantropy program, a starship crewed by "standard" humans is enroute to some unimportant backwater planet to deliver a pantropy team who are "adapted" humans resembling seals more than humans. Due to racial prejudices, tension mounts between the crew and the passengers onboard. When the captain decides to restrict the passengers to their cabins to prevent the situation from escalating, the leader of the adapted humans informs him that the planet ahead is Earth, where the "normal" human form once developed. He challenges the "normal" humans to follow him onto the surface of their ancestral home planet and prove that they are superior to the "adapted" seal people who will now be seeded there—or admit that they were beaten on their own grounds. The story concludes as the captain and his lieutenant silently ponder the possibility that they, being "standard" humans, are just a minority, and an obsolete species.