Hammer in name, but this isn't your typical 1960s Hammer production - The Lost Continent is a slightly odd adventure flick.
Based on a Dennis Wheatley's Uncharted Seas (you can see one of the cast reading it in the opening minutes), The Lost Continent focuses on an old steam boat, one on its way to South America with a crew of rogues, passengers who aren't much better (that's why they're on a dodgy boat) and a cargo of highly explosive (and illegal) material that will explode if it gets wet. Not the best cargo to send by sea, but hey, the captain needs the cash.