Surprises in the Desert
The most implausable plot element, the Civil War Ironclad that sails across the Atlantic and gets lost in Africa, isn't all that far fetched, especially when we consider the benchmark film for all other action adventure stories involves a search for the Lost Ark of the Covenant. The pending ecological disaster subplot dovetails nicely with the treasure hunting plot, which is a plus. I fully expected to be swinging back and forth from maudeline eco-histrionics to cut throat adventure but was pleased with how the script writers, all sixteen of them, managed to segway from one to the other and back again without breaking anyone's neck or stretching credibility too far.
On the Indiana Jones scale of adventure movies, I give it 4 out of 5 fedoras.