Dark day in the deep sea /
by Mary Pope Osborne ; illustrated by Sal Murdocca.
- 1st ed.
- New York : Random House, c2008.
- 106 p. : ill. ; 22 cm.
- Magic tree house ; #39 .
"A Merlin mission." "Stepping Stone book."
When eight-year-old Jack and his seven-year-old 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.