Check out this rugby team from Fiji -- singing a BEAUTIFUL song from their hotel balconies to thank the staff for taking care of them during a mandatory COVID quarantine.

The team is the Kaiviti Silktails -- the guys are currently in Australia to participate in the Ron Massey Cup, a big rugby tournament in New South Wales.

But, since Australia doesn't mess around when it comes to COVID, all players were ordered to quarantine at a hotel for 2 weeks before they're allowed to head into public.

The guys have been holed up at the Sofitel Wentworth Hotel in central Sydney -- and wanted to show their appreciation to the staff ... so they got on their balconies and broke out in song AND IT'S BEAUTIFUL!!!

We're not sure which song they're singing (if you know, feel free to write in and let us know!) ... but it's an incredible sight and these dudes can SANG!!!