A passenger on a dive trip to Rottnest Island has described how people in another boat came begging for help for a dying diver on Sunday morning.
The crew of the dive boat managed to get the 39-year-old victim aboard and fought to save him for 30 minutes but he died in hospital that night.
Jenny Curtis said she was on a Perth Diving Academy trip when a private boat came racing towards them with two men showing the international distress signal and yelling: "Bent diver, bent diver."
She said a diver lay horizontal on the deck and the dive instructors rushed to get the injured man on to the bigger boat. "By the time he got to our boat, he was blue," Ms Curtis said. "They basically started to do resuscitation."
It is understood the Hillarys man had been diving at a depth of 16m near Parker Point when his diving companions noticed he was low on air.
They ascended to the surface but the victim swam off after a fish. His companions spotted him on the surface with pink froth coming out of his mouth, suggesting he suffered from a condition known as arterial gas embolism, when divers do not breathe out as they ascend.
Ms Curtis said she was amazed to watch the Perth Diving Academy crew in action.
"They did everything in their power to save that guy's life," she said. "It was textbook."
The man was taken to the main jetty, airlifted to the mainland by the RAC rescue helicopter and treated in the recompression chamber at Fremantle Hospital but died about 9pm.
The man's death was one of three diving incidents at Rottnest on Sunday as near-perfect diving conditions saw many people in the water.
A 40-year-old woman, believed to be diving with a charter service at Geordie Bay, came to the surface in difficulty about noon and was treated in the recompression chamber.
A 66-year-old man diving at Roe Reef suffered chest pains and was treated at the Rottnest Island nursing post and airlifted off the island by the Royal Flying Doctor Service.
Both were in a stable condition in hospital yesterday.