The Treasure #6
From the Series Treasure Hunters
Chris, Carrie, and Maddison think they know where the San Telmo is. But if they want to find the ship, they're going to have to survive screaming caves, psychotic oceanography professors, dangerous cave floors, ghosts--and a boat with one terrible paint job. But for Aunt Elsie, who set them on this investigation, they're willing to brave anything. The Treasure is book #6 from Treasure Hunters, an EPIC Press series, a division of ABDO.