Swimmers who arrived at a Sydney beach ocean pool found a carcass of a 10m-long adult whale, weighing between 25 and 30 tonnes, perched on the concrete.
The whale is believed to have been dead for two days when it washed over the wall around the pool on Tuesday night, crushing the chain link fence.
The site has become a morbid tourist attraction, with thousands of people turning up to see the carcass and whale rescue workers debating how to remove it from the area.
One of the rescuers told Nine News they may have to cut the carcass into pieces.
Meanwhile the beach has been closed because the smell of the dead whale in the water could attract sharks.
Despite this, surfers were still riding nearby waves.