Incredible footage has emerged of swimmers surrounding a whale only metres from the sand at an Australian beach – but the memorable moment has sparked expert concerns.

The video, taken at Leighton Beach in North Fremantle on the weekend, shows awestruck swimmers just metres from the enormous mammal.

Ori Weiser, who was among those to share the remarkable moment online said it looked as though the whale was going to beach itself.

“He just came in for a quick beer,” Weiser said, responding to concerns about the whale’s health.

“Looked like was beaching himself but after a while, and support from all of us, swam back out happy.”

Commentators were enthralled.

“How lucky are you to be there for it!!” one wrote said. “Magical.”

A whale was spotted near swimmers at Port Beach.

Lawrence Chlebeck, a marine biologist for Humane Society International said the animal’s “torpedo-shaped” body and small pectoral fins suggested it was most likely a sperm whale.

Chlebeck said whales were generally considered peaceful creatures. But they are obviously big and powerful, so his first concern was for the public.

“Even if it was unintentional, people could be very seriously injured by being that close to an animal with that strength and size,” he said.

Chlebeck also had concerns for the whale. He said experts considered anything humans did to animals that changed their behaviour to be a disturbance – “even if it’s them changing the direction that they’re swimming”.

“It definitely wouldn’t have helped it that there were so many swimmers nearby,” he said.

Even just the swimmers’ proximity might have stressed the mammoth marine mammal.

Chlebeck said he understood the temptation to get close but he urged people to keep their distance if they saw a whale of any kind so close to the shore. And while no one appeared to try to touch the whale in the Perth footage, people should never touch an animal in the wild, he said.

“Touching things might seem like it’s harmless, but we have oils and we have bacteria and we have things on our skin that add that other species aren’t used to just the same way around,” he said.

“It’s important to remember that it might seem harmless for these large animals, but really they could be very sensitive to something we could be carrying.”

Whale showed ‘unusual behaviour’

The behaviour at the Perth beach was very unusual for a sperm whale.

“Sperm whales live far off the coast. They dive very deep for squid and things like that, things that live way down in the dark depths, so this is very, very odd behaviour,” Chlebeck said.

Other media has identified the mystery visitor as a humpback. They are known to sometimes come closer to shore.

Regardless of the species, there are numerous emerging ocean threats that can cause distress for all animals.

In the deep, whales used hearing and echolocation to get around, but the ocean was getting louder, thanks to things like seismic testing, oil and gas surveys and military tests, Chlebeck said. Because of that, some animals, including whales, have lost their best way of getting around and some have even had their eardrums ruptured.

That human activity in the ocean could explain why the whale found itself beachside in Perth.

“I’m not necessarily saying that this happened to this individual whale,” Chlebeck said.

“But with the amount of noise in the oceans now and the way that these animals have evolved to navigate around their homes, it’s not unreasonable to say that we are having an impact on the way that they behave, in the way they find the shore and the way they find food.

“It’s very possible that this unfortunately could be a sick or confused animal.”