Chang Island is the largest of the 52-island Koh Chang Marine National Park that was established in 1982 as the 17.national park in Thailand and it is so far one of the least visited of all Thai marine national parks. The park occupies an area of 651 square kilometres in Trat Province on the northeastern side of the Gulf of Thailand and close to the Cambodian border. The park boundaries are poorly defined with some islands, such as Kood Island still privately owned and not under park jurisdiction. Villages, plantations and clearings in the archipelago that existed before 1982 are also outside the authority of parks officials.

The park boundaries are poorly defined with some islands, such as Kood Island still privately owned and not under park jurisdiction. Villages, plantations and clearings in the archipelago that existed before 1982 are also outside the authority of parks officials.

Maak Island, the mext major island south, is covered with coconut groves. For several generations it has belonged to a few affluent local families, but today, more and more of the beach areas are being sold to developers. Maak Island itself has a nice beach on the northwest bay and healthy corals with the best part of Chang Island lying to the north and Kood Island to the south.

Kood Island is the second largest of the island group and heavily forested. Like Chang Island it is adorned with a number of waterfalls. A series of good beaches along the west coast have the nicest sand in Thailand. This island is not part of the park and the forest is losing ground to rubber plantations and tourism development, however, there are still some enormous gum trees, each almost a metre in diameter. The navy has taken exclusive rights to a beautiful area on the southern tip of Kood Island.