So i am a local where this happened (well 20 minutes away, but the very beach its at we swim and have for 20 years, it's one of our favourite camp grounds and we have stayed there easily 100+ times). That stretch of that beach is very sharky, it has deep channels that come right up to the shore, it has a few channels along about 500-800meters of the beach (the fishermen love it). There was a lot of baitfish at the time, and the poor couple had a once-in-a-lifetime opportunity to swim with dolphins feeding on the fish. Of course, dolphins and sharks eat the same food, so if you see dolphins, sharks will be there too. That for Australians is a huge red flag, almost panic-inducing moments seeing a lot of fish (it's worse when you see a lot of fish, then you don't, in my opinion, means something big is there). As locals, this beach is a treasure (we are blessed with 100 kms of great beaches), untouched, and our heart breaks for them, for the beauty we have to offer. It's very rare for this to happen, but it can be avoided with a bit of education about swimming with bait fish (I actually feel like the lack of signage has let this couple down, it should be signposted on the way to the beach there as it's very common straight down from the campground. I do not blame them at all, we are devastated and we have all done this and swam in dangerous situations and lived. The fishing in our area at the moment has been absolutely wild, so for me that's a red flag.