The ashes of Australian man Rye Hunt have returned home to Tasmania after he was cremated in Brazil.

The 25-year-old's body was found washed ashore at Marica near Rio de Janeiro on June 8 following a desperate search after his disappearance 18 days earlier.

Brazilian authorities believe Mr Hunt may have died from dehydration or drowning after attempting to swim while under the influence of recreational drugs.

His uncle Michael Wholohan and girlfriend Bonnie Cuthbert arrived back in Hobart with his ashes on Sunday morning.

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"The family spent the day with them debriefing and sharing memories of Rye," his sister Romany Brodribb told AAP on Sunday.

"We are planning to hold a celebration of Rye's life on July 10 in Hobart for family and friends."

Meanwhile, Edward James Rye was born last Monday night to Ms Brodribb.

"We wanted to give (Edward) a little nod to his uncle," she told The Mercury this week.

The 25-year-old backpacker went missing on May 21 after he separated from his travelling companion Mitchell Sheppard at the Rio airport.

They had an argument after the two took what is suspected to be a highly potent hallucinogen known as NBOMe.

The search for Mr Hunt started on social media when Ms Brodribb and her family could not contact him after he was last seen at the airport.

Police released CCTV footage showing Mr Hunt at the airport and a search led them to an apartment he booked for three days.

It then emerged he likely took a local drug that caused extreme paranoia and anxiety, and may have swum to an island 900m off the coast of Rio.