Due to the fact that they are mammals, Beavers cannot actually breathe underwater. Instead, they can hold their breath for a remarkably long time, sometimes even for as long as 45 minutes! While they average roughly 15 minutes underwater, Beavers have been recorded to stay underwater for upwards of three-quarters of an hour. To put that in perspective, the longest a human has ever held their breath underwater is 24 minutes and 3 seconds. This record is held by Aleix Segura Vendrell, who broke the world record in 2012.