science fiction: 99 Cent Tom Swift and His Undersea Search( sci fi, science fiction, Edgar rice Burroughs, space opera )

A Mr. Dixwell Hardley approaches Tom with a proposition to help recover sunken treasure. Mr. Hardley was on board a ship which was carrying gold to help finance an illegal revolution. When the ship sank, Mr. Hardley overheard the captain recording the coordinates. Now he wants Tom's help to recover the gold and so begins the tale.