[Shaun]

I may be wrong but honestly I'd assume this is some kind of suicide.

Her last tweet seems very ominous in retrospect, and I can't help but wonder if she originally wanted to "take" him with her but then had some last-minute change of heart before doing it and leaving him on the boat.

I don't know, this is obviously all conjecture, but... I don't see how "I left my 4 year old on the boat and went for a swim without the lifejacket and accidentally got swept away" happens. All I know is that if she was indeed depressed, and suicidal, thank god she had some (last-minute) clarity and spared her son.

(Obviously I apologise if it does turn out to be a massive freak accident, it just... makes more sense to me that this is what's transpired)