In 1872, intrepid (fictional) explorer Darcy Delamare disguised herself as a man to claim a place on board the (real life) scientific expedition of the HMS Challenger. She made a record of her findings on the trip, recounting the extraordinary sea creatures she witnessed: creatures that, until then, nobody had believed really existed... Children will delight in discovering the anatomy, behaviour and lifecycles of the Merfolk and how they have hidden themselves from human discovery over millennia.