All dogs swim, right? Well, maybe not.
Although many Rottweilers can and do swim, some are not so keen. Rottweilers are not naturally a water or sporting breed, they are more of a working, herding and guard dog. This does not mean that they don't like water, just that they are not one of the many breeds who necessarily take to it like ducks, due to genetic predisposition. Also, because Rottweilers tend to be heavier set, muscular dogs, they are not especially well designed for swimming. Still, most Rotties take to swimming pretty readily, but some may need a little extra encouragement and instruction to become proficient and learn to enjoy swimming as much as their sporting dog companions.
Rotties are such individual dogs, what is good for one is not necessarily good for another, and taking to the water is no different. So, you will need to see if your dog is a fish or a reluctant rock! If it is the latter, some training to swim may be necessary, especially if you live near water and enjoy water sports and want your dog to be able to safely accompany you and enjoy outings on, and around the water.