Tom Swift and His Undersea Search: The Treasure on Floor of Atlantic

Mr. Damon shows up with a new friend, Dixwell Hardley, who promises wealth from the bottom of the sea. Tom reluctantly agrees to join the search for the sunken steamship SS Pandora and a million dollars in gold coins. In his submarine, the Advance, Tom and his chums must overcome deadly sea creatures, foul weather, accidents and a double-cross from Hardley before reaching his goal (Tom Swift Unofficial Home Page).