Product color is Mary Pope Osborne; illustrated by Sal Murdocca
When Jack and his sister, Annie, join a group of nineteenth-century explorers aboard the H.M.S. Challenger, they learn about the ocean, solve the mystery of its fabled sea monster, and gain compassion for their fellow creatures.
^Mary Pope Osborne (2014). Magic Tree House #39: Dark Day in the Deep Sea, Random House Books for Young Readers. ISBN 9780375837326 (revised Nov 2018)
^Mary Pope OsborneMagic Tree House (R) Merlin Mission Ser.: Dark Day in the Deep Sea : Magic Tree House by Mary Pope Osborne and Magic Tree Osborne (2009, UK-Trade Paper)ISBN 9780375837326 (revised Jun 2021)
^OSBORNE, MARY POPEMURDOCCA, SAL (2015). Magic Tree House #39: Dark Day in the Deep Sea, Random House Books for Young Readers. BiggerBooks. ISBN 9780375837326 (revised Jul 2024)