Originally the Irrawaddy Dolphin lived all along the coastlines of Southeast Asia, up to the Gulf of Bengal and down to the north Australian coasts opposite to Papua / New Guinea. Although he is called after the Irrawaddy River, it's not only a river dolphin. The most sub-populations prefer bays and mouthes of rivers and swim occasionally riverupwards. Others live permanently in rivers, as the population in the Mekong River does. In the Mekong the dolphins come that far riverupwards that they appear in the sout of Laos at Si Phan Don (4000 Islands).
A 2 baht stamp from Thailand (1988) displaying the Irrawaddy Dolphin 'orcaella brevirostris'.
Other populations in Southeast Asia appear in the brackish waters of the Songkhla Lakes (less than 50 individuals), on Borneo (Kalimantan) in Indonesia (Mahakam River, the population was discovered and described first in 1986 and numbered to 77 individuals, only 34 individuals are left at present) and in the Irrawaddy River (officially renamed to Ayeyarwady River) in Burma/Myanmar.
The Irrawaddy Dolphin is member of the family of whales.
Irrawaddy Dolphins usually don't stay long under water, they come up to the surface to catch air every minute or so. But when deep-diving they can stay several minutes under water without taking breath; observations show diving times of up to 12 or 15 minutes. They eat crustaceans, fish eggs and smaller fish and live in small groups of up to six animals, in exceptions more.
The dolphins size reaches up to 2,75m, normally not more than 2,30m and they gain a weight of up to 150kg. Remarkable is that the Irrawaddy Dolphin does not have the typical beak other dolphins have. Their colour varies from dark-grey to white-blue. They are able to change their face expression.
Their swimming speed is rather slow, it doesn't exceed 25km/h in extreme situations. They like to do spyhopping when swimming around.
It's pretty difficult to make a good photo of an Irrawaddy Dolphin. After failing to do so, I sketched one as a substitute. The only halfway reasonable photo I managed to do, after hours of dolphin watching, is the one below.