20,000 baseball cards under the sea

Description:

Roger's friend Kenneth uses an unusual sea vehicle of his own design to take them to an underwater cave, where a cache of old loot gathered by the mermaids turns out to contain a lot of very valuable old baseball cards.

subjects: Fiction,  Juvenile fiction,  Baseball cards,  Inventors,  Buried treasure,  Treasure-trove,  Inventors -- Fiction,  Buried treasure -- Fiction,  Baseball cards -- Fiction,  Beginner,  JUVENILE FICTION,  Fantasy & Magic,  Baseball & Softball,  Sports & Recreation,  Reader,  Baseball, fiction,  Buried treasure, fiction,  Inventions, fiction