I see people who will have their dog swimming and although its always cute to see a dog swimming, in the back of my mind I would be worried about my dog drowning and would want him to wear a life jacket. Do like or use life jackets for your dog?
It sort of depends on how comfortable your dog is around water. Like my dog never went into the water once, so she'd be one we'd have a lifejacket on. If he/she grew up around water, then you're probably ok without a life-jacket for a bigger dog. Even still, I wouldn't take a chance with smaller dogs. You just never know what might happen and it's better to take extra precaution.
Well most dogs are actually naturals in the water and very strong swimmers. After all, where do you think the term "doggie paddle" came from for swimming in the first place? I think it'd be important to have them on dogs who are in stronger currents, though.
I do not know if my dog knows how to swim, but it's unnecessary at the moment based on his life style, so I will only purchase one for him if he is going to use it.