Many incredible species live in the trees. One of those species are sloths. Sloths may seem like a very slow animal but their swimming on the other hand is just the opposite. Looking past the sloth slowness, sloths swim quite fast. Scientific proof shows that sloths swim fast because of their nails. A sloths nails can reach up to 3-5 inches on average. The nails form a web like feature, making them like flippers to sloths, pushing them through the water. Conclusion, sloths swim fast.