To my mind, one of the most successful and wonderful examples of ecotourism, that I think everyone should support if they can, is the program that is run by the people who live near the mountain gorillas in Africa.
There are several countries which contain mountain gorillas, as some of their habitat is on the border between two countries.
On one side, the people have realized how much money they can make from tourism and that it is a sustainable resource, so the local communities protect the gorillas and the environment and welcome people to come see them. On the other, the gorillas are still commonly caught and killed by poachers.
There are only around 800 gorillas left in the world and unfortunately, they don't know where the border is. So, people should support this travel and tourism initiative as much as they can, so that it becomes more and more obvious to everyone that protecting and promoting the gorillas is the way to go in the future.
It's definitively something I'm planning to do in the future.