Thailand covers an area of some 198,000 sq mi, or 514,00 km2, and is the 49th largest country in the world. The country has four distinct geographic regions, with the highest point being Doi Inthanon at 2,565 metres (8,415 ft) found in mountainous north of the country.

The northeast of Thailand, known as the Issan region, is a semi-arid farming area bordered to the east by the Mekong River and Cambodia to the south of the region.

The centre of the country is dominated by the predominantly flat Chao Phraya river valley, in which you will find the vast rich fields. The river runs into the Gulf of Thailand and on its path splits the the countries capital city, Bangkok, in two.

The south consists of the narrow Kra Isthmus, a land bridge that connects main land Asia to the Malay Peninsula. This land bridge also separates the 2 main diving locations, the Andaman Sea from the Gulf of Thailand and provides the set off locations for many of the tropical islands.

The local climate is tropical and characterised by monsoons, making the majority of the country humid for most of the year. The area of Thailand north of Bangkok has a climate determined by three clearly defined seasons. Between November and February the weather is mostly dry with cooling breezes making this an ideal time to visit, March to May sees the winds on the northeast monsoon die down and the temperature increase with even less rain that the previous months. The third season May to November is dominated by the southwest monsoon bring with it a lot of rain.

The southern region of Thailand really has only two seasons, the wet and the dry season. However these seasons do not effect the east and west sides of the peninsular at the same time. On the west coast the southwest monsoon brings rain and often heavy storms from April through to October making the diving season in the Andaman Sea from November to April. On the east coast the monsoon brings most of the high winds and rain between September and January, making the Gulf of Thailand best to dive from March to September.