Marvel Cave is the deepest cave in Missouri.The deepest cave in Missouri, which sprawls over 500 feet below the surface of the Earth, was first discovered by the Osage Nation in the 1500s. Not long after, Spanish explorers in search of riches and the fountain of youth made the journey into the cave and returned empty-handed. The fountain of youth has yet to be found, but riches — albeit from an unexpected source — were discovered by miners in the 1800s. They came to the cave, which was later named Marvel Cave, in search of marble and iron. But instead...