Size: Approximately 514,000 square kilometers.

Topography: Chief topographic features include central plain dominated by Mae Nam (river) Chao Phraya and its tributaries. To northeast rises dry, undulating Khorat Plateau bordered on east by Mekong River. Mountains along northÍÍÍern and western borders with Burma extend south into narrow, largely rain-forested Malay Peninsula. Network of rivers and canals associated with northern mountains and central plain drain, via Chao Phraya, into Gulf of Thailand. Mae Nam Mun and other northeastern streams drain via Mekong into South China Sea. Soils vary. Topography and drainage define four regions: North, Northeast, Center, and South.

Climate: Tropical monsoon climate. Southwest monsoons arriving between May and July signal start of rainy season lasting until October. Cycle reverses with northeast monsoon in November and December, ushering in dry season. Cooler temperatures give way to extremely hot, dry weather March through May. In general, rainfall heaviest in South, lightest in Northeast.

Data as of September 1987