When watching the first video, it seemed that Loki would only go as deep as he still could have his feet on the ground. But on the second video, it does look like he is swimming with the black dog. 🙂
He likes to stay where he can still touch the bottom, but will swim out farther sometimes if a dog he is playing with goes deeper.
We also live on a small lake and though he's gone in the dog park lake without reservation for months, he's always acted like a typical B with our lake, even when chasing the ducks out of the yard. Until today. My father-in-law and husband were tossing in bread and Loki's old kibble for the ducks and fish and wouldn't ya know it? In Loki goes, chasing ducks and eating the bread and kibble! And he went out farther than he's ever gone in the dog park lake, actually swimming out, but of course the ducks were faster 😉