Tantalum is a rare, blue-grey metal that is found deep within the chasms of Ferchiun*. Immune to all but the strongest acids, if more had heard of it would be more sought after. It is nearly as hard as adamantine and holds an edge equally as well. Those few who believed such a tale did not return from their quest to gather any, or if they did, it was not to the homes from which they came.
The heroes are travelling the great seas by ship. One night when the seas are calm and everything seems fine their vessel is eaten by a great whale. The end? No. They wake in the belly of the animal, it is like a great cave. Full of wrecked ships and strange things to be discovered. Will they make it out alive?