The Black Pearl Mystery (The Boxcar Children Series #64)

The Boxcar Children and their grandfather are visiting Hawaii. They help pick pineapples on their cousin Mary's plantation, go snorkeling, and visit a volcano. But they can't figure out why no one will tell them the legend of the black pearl. And who took the diving maps that belonged to cousin Mary's husband? It looks as if the Aldens have another mystery on their hands!