Wildlife tourism helps preserve habitat of the animals being visited. It also employs citizens, which helps prevent poaching and turning habitat into farms. It produces minimal change to the habitat (just dirt roads and a few campsites and lodges) and allows natural behavior of the residents. Our driver stopped our Land Cruiser at a water hole occupied by abou 20 hippos. After several minutes of watching inactivity, this one opened and closed it's mouth several times. I zoomed in and shot a dozen or so frames at the giant jaws gaped wide and then shut.