There was a shock for sun seekers and surfers on sun-kissed Bondi beach as the water turned blood red.
The tides were crimson like a bloody scene from Jaws, and parts of the beach had to be shut while experts investigated the cause of the strange colouring.
Eventually, it was determined that the redness was caused by a type of algae, which usually blooms during the spring and autumn.
The algae has now abated and the beach has reopened. However swimmers are being advised to be cautious given the remaining traces of algae can still cause skin irritation.
Reports suggest the algal bloom killed several fish before it abated, however the precise toll has yet to be established.