Marena has discovered an important clue about a treasure-laden Spanish galleon lost at sea centuries ago, but has no idea how she could search for the ship until a wild series of events lands her, and her older brother Lucas, straight into the hunt. Using her newfound skills from her time aboard the OceanXplorer, Marena bravely navigates the perils of deep-sea exploration, and learns the most important lesson of all--that there is more than one type of treasure.