The Torrent Duck (Merganetta armata) lives in the Andes, and as the name suggests, has a fondness for very fast-moving mountain streams, especially near waterfalls. Obviously it needs to be a very powerful swimmer to fight the current and swim upstream in that, especially as it's a bit on the small side (smaller than a Mallard). Like many duck species, including the recently-covered Mandarin Duck, it makes some rather large demands of its ducklings. But rather than asking them to drop out of a tree cavity at an enormous height, it asks its ducklings to climb out of a crevice in the rocky canyons and inclines where its mother laid the eggs, jump down from the high rocky cliffs, and then go swimming in water so speedy it'd be too dangerous for a human swimmer. And the ducklings do this. How do they keep from being swept away in the fast water? They instinctively search out the eddies behind stones where the current isn't as strong, and they are so buoyant that they (mostly) stay afloat--any that get swept away are retrieved downstream by the parents. And they do this immediately after hatching.