I suppose that it could have been dingo drool.
Since the deceased girl lives in my part of the world there was a TV news segment where they interviewed friends who stayed home and weren’t with her in Australia. They all said she was a strong swimmer, and she had work with firefighting crews so one presumes she was in very good shape. That just deepens the mystery as the location does not look like very dangerous swimming ... you have to wonder if a third party was responsible. A meet-up gone wrong?
“Except for the water in her lungs.”
Fluid, not water. Findings say may be from puncture wounds.