Interesting that you say that.
Here in S Georgia the rivers are the first place the hogs run when pursued by dogs. They hop in the river and then while they float down we have to chase them downstream in what is usually soggy conditions.
Meanwhile the dogs get scattered all over the place.
We guessed that the hogs had been chased into the bay by dogs . The female was obviously confused and she was swimming in circles with the babies trying to follow her.