A SPEARFISHERMAN made the “heart-wrenching” decision to leave his unconscious father in the water off Cairns before swimming for his life.

The 56-year-old man and his 24-year-old son were fishing off Arlington Reef on Friday when their boat drifted away in windy conditions.

As they tried to swim after it, the older man got into trouble. Sergeant Andrew Ibell from Cairns Water Police said the son tried to resuscitate his unconscious father but was forced to make the “heart-wrenching decision to leave” him and try to reach the boat.

A commercial vessel spotted the young man, clinging to a navigation buoy.

“He was very distressed obviously,” Sgt Ibell said on Monday. “Water Police went out and picked him up off that vessel and brought him back to Cairns to be with his family.” It’s thought the father and son were relatively experienced spearfishermen.

But Sergeant Ibell said a boat should never be left unattended.

“Or if it is, you’ve got to have some way of being attached to that vessel so that you can quickly get back on board,” he said.

It took crews just 45 minutes to find the father’s body.

The boat, which is worth up to $50,000, still hasn’t been found. Boaties in the area are being asked to keep a look out for the six-metre aluminium vessel, which has a light-coloured centre cabin and black hull with blue sign writing.

“It’s most likely still floating out there,” Sgt Ibell said. A report will be prepared for the coroner but the father’s death is not thought to be suspicious.