I have three dogs. They all love the water in their various ways.
My middle sized girl loves the water but only to wade. She must be able to see the bottom. But she simply loves to walk around in water. She also loves to 'fish' in that shallow water if there are small fish there. Many places have such types of water we go to. There is water often running in small creeks, etc.
My weenie girl also loves the water, but loves to swim if it's not moving really fast. Since I have her on an extended leash, she will be able to swim that way, but she doesn't chance it.
Because she is a weenie dog, it doesn't take much water for her to be able to swim obviously. She first swam in water that the other two could only wade around in. I'll never forget the look on her face when she felt the bottom leave her feet and realized she was swimming. She swam around a few feet, mostly in a circle very close to me. She was on the extended leash, so I believe she felt safe and appreciated it.
Now, my big guy is a mix of spaniel of some kind and Pyrenees. He LOVES to swim. The problem is that when we are around water enough for him to swim, it's in a leashed area only most of the time. The reason this is a problem is that he is double dog leashed to the middle girl on a leash coupler. The leash coupler is awesome, I highly recommend them to people, it frees up a whole hand and more. I'll save that for another post.
What is the problem is that you recall the middle size girl won't swim. They are in water, and he will pull like crazy to reach the water deep enough to swim, and she will yank him back saying I'm not going in there. Bless his heart, he does try to hold back now. There is only one river walk that we know of that is leash free and we can't go back there very often as it is a two hour drive because I don't live there anymore.