Koh Chang Islands National Park covers the Chang island and other smaller isles within Trat territorial waters. The area has an abundant and thriving coral reef and a spectacular underwater marine environment.

Koh Chang itself is the largest among the 52 islands of Trat. Covering an area of 429 sq. kilometers, it features fine beaches, coral reefs, and plentiful marine life. It is also rich in natural resources, with many hills, forests, waterfalls and streams (the latter being an important source of fresh water). The island also has many exotic fruit orchards.