Are Mermaids Naughty or Nice?
There's nothing like a mermaid movie to get people excited, one way or another. In 1915, Universal Studios was out on Santa Cruz Island in California filming Undine, a movie about mermaids, and it created quite a splash.
Some people objected to the scantily clad actresses playing mermaids. "The picture producer would have done better to have called Undine, Undressed, for never in any film production to date has there been so much female loveliness with so little draping. In fact, there were entire stretches of the picture when the female loveliness wasn't draped at all." – Variety, February 4, 1916
But not everyone agreed. "Although their clothing is scanty (and in some cases, entirely absent), there is nothing about the scenes which can give offense to anyone. Censors will look in vain for something to cut out. (Which does not mean that they will cut nothing.)" – Motion Picture News, February 12, 1916
Unfortunately, this seems to be one of the many silent films that are lost, so we will not be able to judge for ourselves.