Kurt filmed the encounter, as Jai got up close and personal with a large great white shark. "Probably one of the craziest things I’ve ever seen," Jai told Nine News. "The great white came straight up, like face-to-face, and then just turned and kicked away. "It’s probably not the smartest thing to do but, yeah, if you've got the balls to do it, I don’t see why not." The whale carcass floats upside down in the water off Wattamolla Beach in the Royal National Park on Sunday. Credit:Anthony Turner / Surf Life Saving Illawarra

Kurt said their mother was less than impressed with their decision to dive near the whale carcass. "My mum wasn’t very happy about it. When I left, I told her I was going to do it so she was stressing out all day," he said. An alert on the NSW National Parks and Wildlife Service (NPWS) warned that visitors risked a penalty if they chose to swim, snorkel or dive at the beach while it was closed. The agency's Royal National Park manager Shaun Elwood said getting into the water while the carcass remained at the beach was dangerous. "Unfortunately, we’ve seen quite a few instances in the past few days where commonsense has not prevailed," he said.

"The advice of ourselves, the police or Roads and Maritime hasn’t been followed." Authorities may tow the whale carcass out to sea to dispose of it. Credit:Anthony Turner / Surf Life Saving Illawarra The carcass, which was first reported to authorities on Monday, had been wedged on rocks for a number of days. It has now come free and NPWS staff are monitoring the situation. Boats have also come in close to the carcass in recent days. Water police and Roads and Maritime Service staff have been in the area in an attempt to keep vessels away. Mr Elwood said scientists and the Australian Museum were working to identify what sort of whale it was.

"It’s a very large whale . We’re talking an 18-metre long whale, which could potentially weigh between 30 and 40 tonnes," he said. "We have body tissue samples that are getting analysed to help with that identification. It’s not a humpback whale." Mr Elwood said the carcass could be that of a sei whale, but it was too early to say definitively. "The options or the potential species that have initially been raised as possibilities are all very rare in the sense that the recorded incidence or occurrence in NSW is very limited over the past 50 to 60 years," he said. How the whale died is also not known. Mr Elwood said it would be "very difficult" to determine the cause of death.