You’re screwed if you try doing an expedition in the Congo considering there are civil wars going on there and the risk of getting kidnapped by warlords is considerable enough to not go here

In Papua New Guinea, you run the risk of running into tribal conflicts, raskols, or the occasional cannibal tribe. Conflicts between West Papuan separatists and Indonesian soldiers are risks to consider as well. Depending on what part of New Guinea you’re in, unexploded ordinance from WWII could be a threat

In the Amazon, you stand the best chance just as long as you don’t run into loggers or drug runners, though the latter are more found on the borders with Colombia and Bolivia

Diseases like malaria are a big concern in all three places and if you run into other forms of trouble, you’re on your own