Oliver Tree's death in Brazil happened suddenly ... and fans have rushed to social media to watch his final days play out.

The singer-songwriter and his pals posted all about the trip in the days prior to the tragic helicopter crash that took his life ... with Iae Break -- a popular influencer -- sharing videos from Tree's trip.

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Break posted a video of Tree's first time in Brazil ... full of street soccer, seasoned meat, motorcycles, and more fun.

The hilarious clip shows Tree jokingly calling himself Neymar after the famed Brazilian soccer star ... and holding a faux version of the FIFA World Cup trophy.

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Break shared his distress after Tree, YouTuber Gaspi and four others died in a dual-helicopter crash. The caption of his tribute post -- translated to English -- reads, "I can't believe you guys are gone."

As we reported ... Tree, Gaspi and 3 others were in one helicopter which collided with another chopper carrying just the pilot. All six people onboard the two crafts were killed -- and video captured the fiery aftermath.

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It seems Tree was a frequent helicopter passenger ... recently using one to fly into the massive Las Vegas music festival EDC last month.

Tree was 32.

RIP