QUEENSLAND, Australia (WJW) – Beachgoers in Australia were taken by surprise when a large flightless bird swam to shore from the ocean.

According to the Queensland Department of Environment and Science, witnesses first thought the large, dark mass emerging from the water was a turtle or the dorsal fin of a shark.

As seen in the video above, taken by Bingil Bay Campground host Nikita McDowell, the creature turned out to be a southern cassowary, which is often considered the “most dangerous bird in the world.“

The endangered bird sighting was reported to Queensland officials on Oct. 31. Wildlife experts with the Queensland Parks and Wildlife Service called the video “astonishing.”

“Cassowaries can swim and will take to the water to cross from one side of a river to the other, or if they feel threatened by domestic dogs or another cassowary through a territorial dispute,” said wildlife officer Stephen Clough in a media release.

They aren’t sure how long the cassowary was in the water or where exactly it came from.

“Perhaps it entered the ocean around south Mission Beach and was caught by the current or in a rip and swept around to Bingil Bay,” McDowell said in the release.

Officials say there are about 4,000 cassowaries left in Queensland.

According to the San Diego Zoo, cassowaries are large, flightless birds that are closely related to emus. They’re the heaviest bird native to Australia and the second heaviest in the world after the ostrich.

Learn more about them right here.