The Irish Examiner reported Mr Callanan, who has a six-year-old son, had been on business in Thailand prior to the accident at the weekend.
Mr Callanan had been living in Perth, Australia, for six years, working as a project manager with Australian company AMS services and maintenance.
He decided to go diving during his time off.
It was unclear yesterday how the accident happened or whether Mr Callanan was alone at the time.
His body has been recovered, the newspaper reported.
A spokesperson for the Department of Foreign Affairs said they were “providing consular assistance” to the family.
Details were being finalised yesterday (April 14) in relation to bringing Mr Callanan’s body home.