The dorsal fin of the Indo-Pacific Humpbacked dolphin, Sousa chinensis, usually sits on a distictive hump, as here. Eastern populations may have little hump at all, and may even be a separate species. This dolphin, semi-captive in Singapore, is more pale pink and speckled than most, and, along with the shape of the dorsal fin, could be quite old. Other dolphins can be mixes of light gray and brown, and the young "Sousas" generally have more curved dorsal fins.
(Photo courtesy Fundación Omacha, Colombia)

The "Sousa" is about the size of the bottlenose dolphin, but looks and swims quite differently. They surface with their heads up, like this, and may show their flukes as they dive. They prefer to swim slowly in water less than 65 feet deep, and do not seem to be attracted to boats. They may have learned that boats are dangerous in much of their near shore range from Australia to Africa.
(Photo courtesy Fundación Omacha, Colombia)