The Pacific white-sided dolphin (Lagenorhynchus obliquidens), also known as the hookfin porpoise, is a very active dolphin found in the cool or temperate waters of the North Pacific Ocean. This gallery includes images from the Salish Sea, off Vancouver Island, the Straight of Juan de Fuca, Washington and the Kuril Islands, Russia.

The range of the Pacific white-sided dolphin arcs across the cool to temperate waters of the North Pacific. Sightings go no further south than the South China Sea on the western side and the Baja California Peninsula on the eastern. Populations may also be found in the Sea of Japan and the Sea of Okhotsk. In the northern part of the range, some individuals may be found in the Bering Sea. The dolphins appear to follow some sort of migratory pattern – on the eastern side they are most abundant in the Southern California Bight in winter, but further north (Oregon, Washington) in summer. Their preference for off-shore deep waters appears to be year-round. The only known predator of the Pacific white-sided dolphin is the killer whale, but at least one case of predation by the Great White Shark has been recorded.

The total population may be as many as 1 million. However, the tendency of Pacific white-sided dolphins to approach boats complicates precise estimates via sampling.