I've just remembered there's a sequel, 'Beyond the Poseidon Adventure', in which Michael Caine, Karl Malden and Sally Field turn up in their tugboat to try and salvage what they can, being joined by Telly Savalas and his Greek Orthodox mercenaries medics. They find the gold, find a few passengers (Veronica Hamel, Slim Pickens, Mark Harmon), but then the mercenaries find their lost plutonium and it all ends in tears.