In North America, I was familiar with the geology of Precambrian gold deposits, but a tropical setting changed quickly my perception. I had to learn again. The tropical geology is characterized by a lateritic erosion processes, a deep saprolitic profile, and quasi-total lack of outcrops. One lives in a perpetual state of humidity which rotes peoples, shoes, clothes, instruments and food. The drainage water, saturated with iron hydroxides and humic acids, corrodes even a stainless steel.
Body is a blood bag permanently subjected to malaria, typhoid, and fungus attacks.
Piranhas, electric eels, sting rays and himaras populate rivers and creeks. Thousands of aggressive boars tramp the land. A dangerous bushmaster snake stalks on the land and himaralli snake in the water. Passengers can only hope for the best. Where river or creek beds are obstructed by rocks, or dead wood, one must take to trails meandering around fallen trees.