An Amazon Best Book of April 2024 • An IndieNext Pick  A charming fantasy set in an underwater world with magical academia and a heartwarming penpal romance, perfect for fans of  Emily Wilde's Encylopaedia of Faeries  and  The House in the Cerulean Sea. A beautiful discovery outside the window of her underwater home prompts the reclusive E. to begin a correspondence with renowned scholar Henerey Clel. The letters they share are filled with passion, at first for their mutual interests, and then, inevitably, for each other. Together, they uncover a mystery from the unknown depths, destined to transform the underwater world they both equally fear and love. But by no mere coincidence, a seaquake destroys E.'s home, and she and Henerey vanish. A year later, E.'s sister Sophy, and Henerey's brother Vyerin, are left to solve the mystery, piecing together the letters, sketches and field notes left behind—and learn what their siblings’ disappearance might mean for life as they know it.   Inspired, immersive, and full of heart, this charming epistolary tale is an adventure into the depths of a magical sea and the limits of the imagination from a marvelous debut voice. Praise for  A Letter to the Luminous Deep “An underwater treasure-chest to be slowly unpacked, full of things I adore.”  —Freya Marske, author of  A Marvellous Light “A shimmering, delicately crafted delight.”  —H.G. Parry, author of  The Magician's Daughter “A fascinating and charming story told in a uniquely elegant voice.”  —Louisa Morgan, author of  A Secret History of Witches “Both the setting and the story are exquisite.”  —Megan Bannen, author of  The Undertaking of Hart and Mercy