Authorities are working to remove a dead baby whale from an ocean pool in the Sydney suburb of Newport.
National Parks and Wildlife Service spokesman Geoff Ross said it was believed the whale died at sea.
"It's not unusual to see humpbacks at this end of the season; animals that are sick or debilitated, very old animals, or young animals that just aren't going to make it through that rough sea," he told ABC Radio.
"What happens is that they'll die at sea, and usually that's all dealt with by those big predators that are sitting there way off shore."
Rangers now estimate the whale to be 12 metres in length and weighing between 20 to 30 tonnes.
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"It's a mammoth task for council and National Parks and Wildlife to work with," Mr Ross said.
Newport beach local Richard said the whale was floating in the ocean pool.
"I swim every day and I'm not sharing my lane with that," he told ABC Radio.
Police are also at Newport beach urging swimmers to stay clear of the rock pool.
National Parks and Wildlife Service are confident rangers and council will be able to remove the whale on Wednesday.
"I'm sure we'll be able to return that pool to its swimmers by tomorrow," Mr Ross said.
