One of the most important rain forest areas of East Thailand covers the inner parts of Chang Island, the second largest island of the Kingdom. Mountains rising to more than 700 metres, frequent rainfalls and the resulting abundance of waterfalls and streams create an almost impassable interior that has so far escaped mass tourism development.

Tropical rain forest is the scientific term for a specific type of eco-system which includes a unique range of plant and animal species. This is in direct contrast to a jungle which has no similar system of organization.

Southeast Asian rain forests date back as far as 60 million years. No other ecosystem on earth is as rich in variety of flora and fauna. Up to 250 different species of trees can be found in a hectare of virgin rain forest, as opposed to European mixed forest, in which one may find perhaps twelve different species.

Worldwide, tropical rain forests are home to more than 3,000 different species of trees, many as yet, unnamed and undocumented. The same wide variety of species also applies to the animal kingdom. Most of the life exists in the canopy of the trees, as high as 40 metres or more above the forest floor and is therefore extremely difficult to spot during trekking.

In the past, tropical rain forests covered much of the globe.Today, however, most have disappeared. Scientists are concerned that this could have an effect on global climate. As recently as fifty years ago, about 65% of Thailand was covered by virgin tropical rain forest. Today, that figure is around 10% with most of the remaining rain forest existing in the highlands of the north..