The jungle is huge and sparse. Easy, if you know the path. And if you freed the prisoner from the cells in the Keep, he will be there at the start to give you some basic directions. There is not much to see in the jungle, and it's hard going. There are some chests scattered about and hidden for the adventerous of you. There is also an optional boss fight near the exit. While you're travelling through the jungle, take care not to exit the jungle at an edge unless it's the edge with the path exiting the jungle, or you'll have to start over. Here is a map of the jungle: