AllMovie

When Gilligan (Bob Denver) stumbles upon a hot water spring, the other Castaways are exuberant: At long last, their huts will be supplied with hot-and-cold home plumbing. But the Professor (Russell Johnson) isn't so happy, concluding that the steaming water may well be the precursor to a violent volcano. As a result, the Castaways construct a makeshift bomb in hopes of neutralizing the volcano--but it may already be too late!