This is an issue devoted to the majesty, mystery and magic of oceans. We are thrilled to be bringing together a truly excellent group writers and illustrators to chart a subject that is enormously important. In the pages of this issue we explore the reasons the oceans mean so much to our lives and our imaginations – from mythical and monstrous beasts of the deep to the real-life heroes of marine biology, this is an issue bursting with stories. Read the pledges of a wave of incredible authors, learn about the fabulous young ocean heroes of today and be guided by our wonderful guest editor, Lauren St John, on how you can become an ocean activist. This is definitely an issue to dive straight into.