I went to YouTube and searched for "rafting on the rio" hoping to find the song, and what I actually found were videos of people rafting on the Rio Grande river in Jamaica (among other rivers of the world; there are lots of them whose names start with "Rio—"). I'm guessing the local people have been entertaining tourists this way for generations. The rafts are made of bamboo, and are only about 3 feet wide at the front where the raft-poler stands, wider at the back where the passengers sit. It looks as if it might not have changed much since Percy French's day.

If you want to see what inspired Percy French, watch this or any of these.

There is even a song in this video called "Rafting on de Rio Grande" but I don't think it's Percy French's song; it sounds like it's in Creole.