TopographyThe 51 islands of the park archipelago lie in the Andaman Sea from 20-70 km.. off the extreme southwest coast of peninsular Thailand. The topography is mostly mountainous with a few broad plains and valleys. Semi-evergreen rain-forest blankets about 60 percent of the island, and pure mangrove swamps are found in several areas. Long sandy beaches lie along the western coast from Pante Bay to Makham Bay, and at Talo Udang Bay in the south.Tarutao is a Malay work meaning old, mysterious and primitive.
Preliminary geological work has borne out the first of these adjectives. Much of Tarutao is composed of very old Cambrian sandstone. The northern and southeastern portions of the island consist of limestone rock. Most of the caves on the island are formed in limestone rock.The Adang-Rawi group of islands lies about 50 km.. west of Tarutao and includes Adang, Rawi, Dong and Lipe. Adang Island. with a steep and rugged landscape almost completely covered by tropical rainforest, may be the most wild and appealing of the islands. Sparkling clear water and superb coral reefs provide habitat for a wide variety of marine life forms, including many brightly colored fish. Beautiful beaches consist of quartz derived from Adang's Cretaceous granite makeup and coral fragmants. Several waterfalls plummet down Adang's eastern slopes in times of heavy rain. 
Climate
Tarutao and the west coast of peninsular Thailand are subject to a monsoon climate.
In the summer months high temperatures in central China cause the air to rise, thus creating a massive low pressure area. This draws wind from the cooler area over the Indian Ocean. The winds coming off the Indian Ocean pick up moisture and dump heavy rains on the west coast of peninsular Thailand from May through October. Normally 250-400 mm. of rain falls in each of these months. The other six months of the year receive little or no rain. Total yearly rainfall averages about 2500 mm. The monsoon winds make boat travel dangerous from May through October; that is why visitors are encouraged to come to the park from November through April.
The mean yearly temperature is between 27 and 28 degrees C. 
The warmest month of the year is April, with the April mean about 29 degrees C. High temperatures in April may be 35 degrees C. or more. November and December are the coolest months of the year with mean temperatures of about 15 degrees C.The mean yearly humidity is about 80%. It is highest in September, October and November and averages about 85%. Humidity is lowest in February and March, varying from 70-72%. The climatic data recorded here was not taken on Tarutao. It is based on data actually collected at Phuket and Trang, and is thus not completely accurate. But it is unlikely that the actual values for Tarutao would be much different.In rainy season, the national park will be closed (Adang - Rawi Islands) during 16 May - 15 November every year for visitors safety.
