Nicknamed as the "river-pig", finless porpoises look round and chubby. They are grey in color and snout-less. Their most distinct feature is that they lack a dorsal fin; instead, they have a wide (about 48 to 120mm wide) dorsal groove that begins just ahead of mid-back and extends to the tailstock.

Indo-Pacific finless porpoises can be found in the southern and eastern waters of Hong Kong. We can sometimes find them in areas between the southern side of Lantau Island and Lamma Island.  The population of  finless porpoises in the Pearl River Estuary (including Hong Kong) still remains largely unknown as the species have no dorsal fin and are relatively shy, they seldom approach boats or exhibit aerial behavior. Hence, they are very difficult to spot or survey compared to Chinese White Dolphins.

Major threats that they are facing include: fishing net entanglement, habitat loss and disturbance, marine traffic and pollution.