The victims were snorkelling at about 10.25am Australian time in the Hook Passage, off Airlie Beach, when the incident happened.

The BBC reports one of those involved, a 28-year-old, had their foot bitten off while a 22-year-old suffered serious leg injuries.

A Queensland Ambulance Service helicopter took the patients to Mackay Hospital, where they are in a serious but stable condition.

“Our first thoughts are with the two people involved in the incident and their welfare, as well as the other passengers and crew on the boat,” a spokesperson from Tourism Whitsundays said.

https://twitter.com/QldAmbulance/status/1189001991898320896

They also commended the “lightning response” of the emergency services: “Their efforts have ensured the two people have been able to receive expert medical treatment very quickly.”

The Whitsunday Islands have hit headlines for a spate of shark attacks in recent times – a 33-year-old man died last November and a 12-year-old had her leg amputated in September 2018 following an attack.

Unmanned baited drum lines were installed in response, but were later removed due to concerns about other marine life.