The Gulf of Tonkin is the northern arm of the South China Sea. Phoebe Tonkin comes from Australia, which is much farther south. After studying dance (at four!) and theater, she landed a role in the series H2O: Just Add Water, in which she played one of three teenage girls who, after a supernatural-ish incident, become mermaids after ten seconds of wetness. (Had this been a risqué show instead of a fantasy show for kids, they could have named it Ten Seconds of Wetness.) H2O ran for three years; after that, she relocated to the States and won a role in The Secret Circle, a short-lived witches’ tale on The CW, followed by five seasons of The Originals, a spinoff from The Vampire Diaries.
Phoebe also did one music video: “Don’t Let Go” by Miles Fisher (2011):
Looks vaguely supernatural there, too.