William Carty and Craig Currie were retrieved from Loch Awe within a few hours of a boating tragedy in March 2009. All attempts to resuscitate them failed.
But Mr Carty's brother, Stephen, and friend Thomas Douglas, who both died after the group's small glass-fibre boat capsized in thick fog, remained missing despite repeated underwater searches.
Glasgow men Craig Currie, 30, Thomas Douglas, 36, William Carty, 47, and Stephen Carty, 42, died in the freezing waters of Loch Awe, as they headed to a shoreside camp after a night out at the Tight Line pub in March 2009.
But Stephen Carty and Thomas Douglas were not found until May 31 last year, when their bodies surfaced near an island in the loch.
Sergeant Ian Bell, 43, who is in charge of Strathclyde Police Underwater Unit, speaking on day 15 of a
Fatal Accident Inquiry at Oban Sheriff Court, said his team members were "exhausted" after carrying out day after day of dive searches in the bitterly cold loch.
He explained that, without any buoyancy aids, the bodies would sink to the bottom and some
parts of the search area were 34 metres deep - too deep for the team to dive in safety.
Sgt Bell told Sheriff Douglas Small that sonar searches were used in deep areas, but Sgt Bell said was not a guaranteed method of finding human bodies.
The initial dives were stopped after nine days.
Additional searches were carried out by officers from Strathclyde and Grampian police forces.
The inquiry continues today.