By 6.30pm the search had been suspended for the day, according to a police spokeswoman. Efforts will resume on Wednesday.
The pair had awoken to find their boat drifting near the small outcrop, off North Keppel Island, when they rushed to action.
“They’ve then got onto their inflatable raft and rode out,” acting Senior Sergeant Amanda Warby told media Tuesday afternoon.
“Due to the conditions, they were being swept further away from their vessel, so they attempted to get into the water and swim to their vessel.”
“I believe it was quite windy, which made their efforts to get back onto the boat a struggle.
“They let off a flare, at which point our search-and-rescue [team] were notified.”
Sergeant Warby said the 62-year-old was suffering from exhaustion and shock, with authorities remaining “hopeful” the missing man would be found.
Police had earlier believed the two men fell overboard and only one man was able to swim back.