Mountainous Ko Chang is the largest of the 50 or so islands that form the Ko Chang National Marine Park, which covers an area of 650 sq km (250 sq miles), two-thirds of which is ocean. Mangroves, cliffs, and clear waters make this one of Thailand’s most scenic islands and the ideal place for a varied holiday. Increased development means that Ko Chang now has no shortage of quality hotels, resorts, and spas.

Since Thai-Chinese agricultural families first settled on Ko Chang in the mid-19th century, most of the island’s wildlife has been destroyed, although some small mammals, including the barking deer, stump-tailed macaque, and small Indian civet, remain. Also resident are some 75 bird species, and reptiles and amphibians such as monitor lizards, pythons, king cobras, and the endemic Ko Chang frog.

Inland exploration is difficult because of the rugged terrain. The coast road, which was begun in the early 1990s, is the first construction to improve accessibility on the island. Ko Chang’s best beaches are on the west coast, especially along Ao Sai Khao, where the shell-sprinkled, bungalow-lined Hat Sai Khao  (“white sand beach”), the island’s longest and busiest beach, is located. An information center on the beach arranges boat trips, fishing, and snorkeling. Most guesthouses also offer fishing, snorkeling, and motorcycle rental. Hat Khlong Phrao , south of here, is more attractive and quieter. Nearby is a fishing village, Ban Khlong Phrao. Because tourism is growing only gradually on the island, fishing is still the main industry.

The beaches in the south are still relatively isolated. Of these, the beach at the sheltered bay of Ao Bang Bao , in the southwest corner, is particularly beautiful. East of here is a long beach encircling a bay, Ao Sa Lak Phet, where there are a few fishing villages and bungalows. The wrecks of two Thai Navy ships can be visited off the coast here.

Of the island’s many waterfalls, two are worth the hike. On the east coast, near the park headquarters, is the three-tiered Than Mayom waterfall , which has good views of the island. The other is Khlong Phlu waterfall , along Khlong Phrao on the west coast. The uppermost level, accessible by a gentle 3-km (2-mile) hike, has a freshwater pool.

For snorkelers, divers, and day-trippers there are stunning smaller islands off the coast of Ko Chang, with a good variety of hard and soft corals and a proliferation of giant clams.

Ko Kut , the second largest island within the group, falls outside the park boundaries. It has excellent beaches and breathtaking waterfalls.

The rocky, coral-lined coast of Ko Wai , south of Ko Chang, is popular for fishing. Around Ko Rang , farther south, is a cluster of rocky coral islets.

Ko Mak , a predominantly flat island, is covered mainly in coconut plantations. It has a secluded beach on the northwest bay, a fishing village, and good coral reefs.

Northeast of Ko Mak is the coconut-fringed Ko Kradat , a tiny island with some of the prettiest beaches in the island cluster. Although the entire island is a privately owned resort with expensive hotels, bungalows can also be hired.

Sandflies and mosquitoes are a problem on the islands, so precautions are necessary.