We learned about the existence of mermaid tails for swimming a couple of years ago at the AQUANALE fair in Cologne, Germany, thanks to Chinese entrepreneurs. We thought it was a passing phenomenon, eccentric and even a little kitsch, a toy for girls. Instead we discovered that this practice is not only playful but also sporty and has a name – mermaiding – and that there are even courses to practice it in a workmanlike manner. Incredible!!! There are two levels: the basic one, in which you learn to use the tail on the surface, and the advanced one, in which you get to explore the seabed by swimming in apnea. Mermaiding tones the body, improves breathing, circulation and mood, because it is very funny.