Osborne, Mary Pope <br/><br/>
Dark day in the deep sea / 
by Mary Pope Osborne ; illustrated by Sal Murdocca. 
 - 1st ed. 
 - New York :  Random House,  2008. 
 - 196 p. 
 - Magic tree house #39 .
<br/><br/> 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. 
<br/><br/><label>ISBN: </label>9780375837319 
<br/><br/><label>LCCN: </label>2007029717 
<br/><br/><label>Subjects--Topical Terms: </label><br/>Oceanography--Fiction.<br/>Challenger (Ship : 1872-1876)--Fiction.<br/>Tree houses--Fiction.<br/>Compassion--Fiction.<br/>Time travel--Fiction.<br/>Magic--Fiction.<br/>Brothers and sisters--Fiction.