Why do most dogs swim good?

Dogs don't inherently know how to swim. Whether or not a dog is good at swimming is determined by its breed and individual characteristics, such as body type and temperament. Some breeds have physical features that make them more suited to swimming, such as water-resistant coats, webbed feet, and long tails that act as rudders. Additionally, some breeds have been selectively bred for water-related activities, such as retrieving and water rescue, which can make them more proficient swimmers. However, not all dogs are natural swimmers, and some may require training to build confidence in the water and learn proper swimming techniques.