TOM IS IN DEEP-SEA TROUBLE... Tom. Bud, and Yo are on the S.S. Nestor, a Swift Enterprises research vessel, to witness Mr. Swift testing his submersible, the Verne-1. Mr. Swift plans to use the Verne-1 to place a network of seismometers on the sea floor to detect underwater earthquakes, volcanic eruptions, and other phenomena that might generate tidal waves on the ocean's surface. But when an unexpected storm hits and the S.S. Nestor looses contact with the Verne-1, it's up to Tom to save his father.