According to research and the source information for this post, yes they can.
Sloths are one of the slowest animals in the world. They are well-known for conserving their energy and moving slow, but like this author they have a natural ability to swim. Again like this author they can move up to three times faster in water than on land.
It is said the reason for this is due to their diet of leaves, which produces large amounts of gas in their stomach, helping them to keep buoyant in water. This author does not eat leaves.
Sloths can also hold their breath underwater for as long as 40 minutes, and they do this by depressing their already slow metabolism, resulting in their heart rate falling to less than a third of its normal rate.
Comparing sloths to the Atlantic Spotted Dolphins (and not because both animals have a natural looking smile), these animals can dive up to 61m (200ft) and have been recorded holding their breath for up to ten minutes, meaning that the sloth can indeed hold its breath longer than a dolphin.
