Footage shared online appears to show swimmers at a beach in western Australia approaching a sperm whale swimming “dangerously close” to the shore.
In a rare moment captured on camera, the large mammal neared shallow waters, attracting crowds of spectators, before going back out to sea at Leighton Beach, near Perth.
Marine biologists warned that the animal's behaviour was “unusual and perilous” and warned swimmers that approaching sperm whales in similar situations was risky.
Marine biologist Dr Natalie Sinclair told the BBC: “The proximity of individuals to the whale poses risk, not only to the animal, but also to the people involved.”
The whale has since become stranded at the Naval Memorial Park at the Rockingham Foreshore, further down the coast in Western Australia.
The Department of Biodiversity, Conservation and Attractions (DBCA) confirmed it is the same whale.
In a Facebook post, Parks and Wildlife Service, Western Australia said: “Our priority is the whale's welfare and to avoid prolonging its suffering.
“Together, DBCA and Perth Zoo staff are carefully considering and planning an appropriate course of action to ensure the most humane outcome for the whale."
The beach has now been closed off to the public as authorities respond to the distressed sperm whale around 50 to 70 metres offshore, reported ABC.
Officials have said the whale may need to be euthanised because of its condition, and urged members of the public to avoid trying to spectate, saying it could cause the animal further distress.
The Department of Biodiversity, Conservation and Attractions has also issued a warning to water users that the whale may attract sharks.
Sperm whales are rarely seen close to shore. They are amongst the largest animals on the planet and can live for up to 70 years.