Myanmar, a republic in South-East Asia, bounded on the north by Tibet Autonomous Region of China; on the east by China, Laos, and Thailand; on the south by the Andaman Sea and the Bay of Bengal; and on the west by the Bay of Bengal, Bangladesh, and India. It is officially known as the Republic of the Union of Myanmar. The coastal region is known as Lower Myanmar, while the interior region is known as Upper Myanmar. The total area of the country is 676,578 square km (261,227 square miles).

A horseshoe-shaped mountain complex and the valley of the Ayarwaddy (Irrawaddy) River system are the dominant topographical features of Myanmar. The mountains of the northern margin rise to 5881 meters (19,296 ft.) atop Hkakabo Razi, the highest peak in Southeast Asia. Most of the mountain systems have northern to southern axes. The ArakanYoma range, with peaks reaching more than 2740 meters (about 9000 ft), forms a barrier between Myanmar and the subcontinent of India. The Bilauktaung range, the southern extension of the Shan Plateau, lies along the boundary between southwestern Thailand and southeastern Lower Myanmar. The Shan Plateau, originating in China, has an average elevation of about 910 meters (about 3000 ft.).

Generally narrow and elongated in the interior, the central lowlands attain a width of about 320km (about 200 miles) across the Ayarwaddy-Sittaung delta. The delta plains, extremely fertile and economically the most important section of the country, cover an area of about 46,620 sq. km (18,000 sq. ml.). Both the Arakan (in the northwest) and the Tenasserim (in the southwest) coasts of Myanmar are rocky and fringed with islands. The country has a number of excellent natural harbors.
 

Reference - Ministry of Hotel and Tourism