23. “The Glass Bottom Boat” (1966)
Starring Rod Taylor and Doris Day, Frank Tashlin’s instantly lovable 1966 rom-com ranks low on this list not because it’s lacking in quality, but because its connection to mermaids is limited. That said, its inclusion speaks volumes to just how irresistible “Glass Bottom Boat” can be. When aerospace engineer Bruce Templeton accidentally hooks Jennifer Nelson, a diver dressed as a mermaid, off the coast of Catalina, they embark on a whirlwind love-hate relationship. Their passionate affair continues at the office where Jennifer and Bruce both work, inadvertently catching the attention of the CIA.