“The drowning could have been due to simple mishap, a rip current, undertow, or even a toxic reaction to venom from a jellyfish sting or the like. Her body would have naturally floated and could have easily been drawn ashore by wave action.”
Or maybe dingos killed her. This would be the third fatal attack at that beach.
I am no expert on Australian wildlife, but I have not heard of dingoes drowning humans.