Irwin Allen produced both, two years apart, and the second is the first done bigger. Poseidon's survivors climb up through an upside-down ship; Inferno's climb down through a burning tower, and the physical logic of the ordeal is the same reversed. The cast structure is repeated deliberately: a large ensemble of names, an authority figure who is wrong, a practical outsider who is right, and deaths distributed so that nobody is safe. Inferno went further by combining two competing novels and two studios into one production, which was the industry's answer to how well Poseidon had done.
