This delightfully saucy short story by Naomi Novik, which she calls a blend of Orlando, Georgette Heyer, and the Atlantis myth. It was first published in the Fast Ships, Black Sails anthology edited by Anne and Jeff VanderMeer — an anthology of pirate stories. Everyone should love pirate stories, particularly this one, which starts off with the most charming worldbuilding:
Lady Araminta was seen off from the docks at Chenstowe-on-Sea with great ceremony if not much affection by her assembled family. She departed in the company of not one but two maids, a hired eunuch swordsman, and an experienced professional chaperone with the Eye of Horus branded upon her forehead, to keep watch at night while the other two were closed.
Sad to say these precautions were not entirely unnecessary. Lady Araminta—the possessor of several other, more notable names besides, here omitted for discretion—had been caught twice trying to climb out her window, and once in her father’s library, reading a spellbook. On this last occasion she had fortunately been discovered by the butler, a reliable servant of fifteen years, so the matter was hushed up; but it had decided her fate.
… and gets more rollicking and whimsical from there.