Blake Griffin -- PERFECT BACKFLIP ... During Croatia Vacation

If basketball didn't work out, Blake Griffin coulda been a gymnast ... because the guy hit a PERFECT backflip during a beach session in Croatia -- and the whole thing was caught on video.

Blake's on vacation in Croatia with Clippers teammate DeAndre Jordan -- and both decided to test their acrobatics.

Blake went first -- killed it.

DeAndre went second ... NOT BAD EITHER ... but he's clearly the Aly Raisman to Blake's Gabby Douglas.