For me the answer is volunteer work in environmental and animal conservation projects. I find a project in a place that I would like to visit and make my contribution towards the environment by working in a project. It is also excellent way to get to see more than normal tourist and gets me near the nature and animals.
Since I started this way of ecotravelling, I have been to Galapagos Islands, Thailand, Australia, Costa-Rica and Carriacou, a small island in Caribbean. Most of these places I have chosen because they offer projects in protecting sea turtles.
Here in Carriacou, I am working especially with two critically endangered sea turtle species; leatherback and hawksbill. I help with measuring and tagging the nesting females, protect the eggs from poaching and natural dangers and finally I sometimes get to see the little hatchlings go out to the sea.
I find this way of travelling very satisfying. I get to see more than what a "tourist" sees of the place and I can do some good with my time. And it is not all just work and no fun. In volunteer projects there is always some time to get around and do stuff you enjoy the most.
I have still 2 weeks to go here in this project, but I am already starting to think about my next project: maybe animal sanctuary in South Africa or Bolivia. I would be able to work with many different animals and help to nurse them back to health and release back to the wild. That would be so awesome!
More about volunteer projects www.ekomatkaajat.fi/english