Hook is Steven Spielberg's answer to the pondering of what would happen if Peter Pan, the boy who's not supposed to grow up, does. In general this movie was not received well by the box-office, but I personally love this movie because it approached James Barrie's classic tale from a different point-of-view, at the same time paying great respect to the source material. In many ways, Hook's portrayal of certain characters and events is actually more accurate than the 2003 live-action Peter Pan film. But I disgress.
Mermaids were a part of the original Peter Pan story, so they were aptly given a cameo in Hook. (Which is more than I can say for the Indians, arrr.) Their cameo is brief, as cameos tend to be, and the purpose of their short appearance was to help Peter Pan/Banning when he was accidentally pushed overboard Hook's ship into the sea. The designs of these particular mermaids were quite detailed, especially if you note their hair and body art, and it would have been awesome if we'd seen more of them. Still, what little we see of them and their underwater movements was nicely done and beautifully organic.