Mr McGarry was a former editor of the Vanuatu Daily Post, and a citizen of Vanuatu after working in the region for decades.
His workplace announced the news on social media, with colleague Aubrey Belford describing him as a "brilliant editor".
"Words cannot convey how devastated we are by this loss," said OCCRP Editor in Chief Miranda Patrucic.
"Dan was so much more than an editor who worked with local journalists and helped build our reporting teams ... he was beloved because he truly cared about the mission and the people he worked with.
"He possessed a bottomless well of patience and is irreplaceable as a mentor and leader."
Mr McGarry's journalism exposed corruption and dubious dealings in one of the world's most under-reported regions, including the 2022 Vanuatu citizenship granted to alleged rapist and influencer Andrew Tate.Â
A 2024 OCCRP investigation with In-Depth Solomons showed former prime minister Manasseh Sogavare had built up a multi-million dollar property empire.
The Canadian-born journalist fell ill after a work assignment in Papua New Guinea last month, and was evacuated to Australia for medical care.
Mr Belford said he was with by his wife Georgeline on Wednesday.
"He is mourned not just by his family, but also by the second family he built among the Pacific's journalists," Mr Belford said.
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