Burma proper is encircled on three sides by a wall of mountain ranges. The Arakan Yomas starting from Cape Negrais extend northwards more or less parallel with the coast till they join the Chin and Naga hills. They then form part of a system of ranges which curve north of the sources of the Chindwin river, and with the Kumon range and the hills of the Jade and Amber mines, make up a highland tract separated from the great Northern Shan plateau by the gorges of the Irrawaddy river. On the east the Kachin, Shan and Karen hills, extending from the valley of the Irrawaddy into China far beyond the Salween gorge, form a continuous barrier and boundary, and tail off into a narrow range which forms the eastern watershed of the Salween and separates Tenasserim from Siam. The highest peak of the Arakan Yomas, Liklang, rises nearly 10,000 ft. above the sea, and in the eastern Kachin hills, which run northwards from the state of Möng Mit to join the high range dividing the basins of the Irrawaddy and the Salween, are two peaks, Sabu and Worang, which rise to a height of 11,200 ft. above the sea. The Kumon range running down from the Hkamti country east of Assam to near Mogaung ends in a peak known as Shwedaunggyi, which reaches some 5750 ft.
There are several peaks in the Ruby Mines district which rise beyond 7000 ft. and Loi Ling in the Northern Shan States reaches 9000 ft. Compared with these ranges the Pegu Yomas assume the proportions of mere hills. Popa, a detached peak in the Myingyan district, belongs to this system and rises to a height of nearly 5000 ft., but it is interesting mainly as an extinct volcano, a landmark and an object of superstitious folklore, throughout the whole of Central Burma. Mud volcanoes occur at Minbu, but they are not in any sense mountains, resembling rather the hot springs which are found in many parts of Burma. They are merely craters raised above the level of the surrounding country by the gradual accretion of the soft oily mud, which overflows at frequent intervals whenever a discharge of gas occurs. Spurs of the Chin hills run down the whole length of the Lower Chindwin district, almost to Sagaing, and one hill, Powindaung, is particularly noted on account of its innumerable cave temples, which are said to hold no fewer than 446,444 images of Buddha. Huge caves, of which the most noted are the Farm Caves, occur in the hills near Moulmein, and they too are full of relics of their ancient use as temples, though now they are chiefly visited in connexion with the bats, whose flight viewed from a distance, as they issue from the caves, resembles a cloud of smoke.
Of the rivers of Burma the Irrawaddy is the most important. It rises possibly beyond the confines of Burma in the unexplored regions, where India, Tibet and China meet, and seems to be formed by the junction of a number of considerable streams of no great length. Two rivers, the Mali and the N'mai, meeting about latitude 25° 45′ some 150 m. north of Bhamo, contribute chiefly to its volume, and during the dry weather it is navigable for steamers up to their confluence. Up to Bhamo, a distance of 900 m. from the sea, it is navigable throughout the year, and its chief tributary in Burma, the Chindwin, is also navigable for steamers for 300 m. from its junction with the Irrawaddy at Pakôkku. The Chindwin, called in its upper reaches the Tanai, rises in the hills south-west of Thama, and flows due north till it enters the south-east corner of the Hukawng valley, where it turns north-west and continues in that direction cutting the valley into two almost equal parts until it reaches its north-west range, when it turns almost due south and takes the name of the Chindwin. It is a swift clear river, fed in its upper reaches by numerous mountain streams.
The Mogaung river, rising in the watershed which divides the Irrawaddy and the Chindwin drainages, flows south and south-east for 180 m. before it joins the Irrawaddy, and is navigable for steamers as far as Kamaing for about four months in the year. South of Thayetmyo, where arms of the Arakan Yomas approach the river and almost meet that spur of the Pegu Yomas which formed till 1886 the northern boundary of British Burma, the valley of the Irrawaddy opens out again, and at Yegin Mingyi near Myanaung the influence of the tide is first felt, and the delta may be said to begin. The so-called rivers of the delta, the Ngawun, Pyamalaw, Panmawaddy, Pyinzalu and Pantanaw, are simply the larger mouths of the Irrawaddy, and the whole country towards the sea is a close network of creeks where there are few or no roads and boats take the place of carts for every purpose. There is, however, one true river of some size, the Hlaing, which rises near Prome, flows southwards and meets the Pegu river and the Pazundaung creek near Rangoon, and thus forms the estuary which is known as the Rangoon river and constitutes the harbour of Rangoon. East of the Rangoon river and still within the deltaic area, though cut off from the main delta by the southern end of the Pegu Yomas, lies the mouth of the Sittang. This river, rising in the Sham-Karen hills, flows first due north and then southward through the Kyauksè, Yamèthin and Toungoo districts, its line being followed by the Mandalay-Rangoon railway as far south as Nyaunglèbin in the Pegu district.
At Toungoo it is narrow, but below Shwegyin it widens, and at Sittang it is half a mile broad. It flows into the Gulf of Martaban, and near its mouth its course is constantly changing owing to erosion and corresponding accretions. The second river in the province in point of size is the Salween, a huge river, believed from the volume of its waters to rise in the Tibetan mountains to the north of Lhasa. It is in all probability actually longer than the Irrawaddy, but it is not to be compared to that river in importance. It is, in fact, walled in on either side, with banks varying in British territory from 3000 to 6000 ft. high and at present unnavigable owing to serious rapids in Lower Burma and at one or two places in the Shan States, but quite open to traffic for considerable reaches in its middle course. The Gyaing and the Attaran rivers meet the Salween at its mouth, and the three rivers form the harbour of Moulmein, the second seaport of Burma.