The Irrawaddy Delta or Ayeyarwady Delta lies in the Irrawaddy Division, the lowest expanse of land in Myanmar that fans out from the limit of tidal influence at Myan Aung to the Bay of Bengal and Andaman Sea, 290 km to the south at the mouth of the Ayeyarwady River. The delta region is densely populated, and plays a dominant role in the cultivation of rice in rich alluvial soil as low as just 3 metres above sea level, although it also includes fishing communities in a vast area full of rivers and streams. On 2 May 2008, the delta suffered a major disaster, devastated by Cyclone Nargis, which reportedly killed at least 77,000 people with over 55,900 missing, and left about 2.5 million homeless.
The Irrawaddy Delta comprises the main arms of Pathein River, Pyapon River, Bogale River, and Toe River. Mawtin Point, formerly Cape Negrais, is a famous landmark in the Irrawaddy Division, and it also marks the south west end of Myanmar. The highest point of the delta, Waphu Mount 404 m (1,325 ft) lies between Pathein and Mawtin Zun (point), on the western strip of the delta. A major portion of the area is covered with low-lying lands just 3m above sea level. This alluvial plain is bounded to the west by the Rakhine Yoma and to the east by the Bago Yoma. It is dissected into peninsulas and islands by the large southward flowing rivers which are subject to tidal intrusion. The lower seaward third of the delta is completely flat with no local relief and stretches for 130 km from east to west.
The waters of these rivers are very turbid due to a heavy silt load they carry and the sea is very shallow with depths less than 5.5 m across the coastline and in the east for a distance of up to 28 km offshore. As a result of constant accretion into the sea, the delta is advancing at a rate of 5–6 km per 100 years, equivalent to about 1,000 hectares per year.