The bodies of two Castlebar men recovered off Inisbofin, Co Galway, have been transferred to Galway University Hospital.
An investigation has been opened by gardaí into the deaths.
The men, who are understood to be in their 50s, were recovered from the water this morning just off the island and were later taken to hospital by the Coastguard helicopter.
It is understood the men, who are believed to be from Co Mayo, arrived on the island by dinghy yesterday after mooring their larger boat offshore. They later left the island on the dinghy to make their way back to their boat.
It is not clear if the men, who were wearing lifejackets at the time, reached the motor boat.
Gardaí are trying to establish what happened. Post mortem examinations will take place later today.