Pachena Bay is located 13 km (8.1 mi) south of Bamfield in Pacific Rim National Park at the southern end of Vancouver Island, British Columbia, Canada.

"This word is derived from the Nitinaht Indian name for the site of Port Renfrew, but by mistake, the anglicized name Pachena was applied to a point further up the coast that had a nearly identical configuration.

'[1] Pachena Bay adopted in the 5th Report of the Geographic Board of Canada, 30 June 1904, as labelled on British Admiralty Chart 592, 1861 et seq, and on John Buttle's "Map of the Country between Barclay Sound & Nanaimo" by the Vancouver Island Exploring Expedition, 1864 (plan 2T67).

"[1] Pachena Bay is home to the Huu-ay-aht First Nations village of Anacla, "which aboriginal oral history says was devastated when an ancient earthquake convulsed the West Coast of North America.

"First Nations from Vancouver Island to Northern California describe the earthquake and tsunami in similar legends and artwork involving a life-and-death struggle between a thunderbird and a whale that caused the earth to shake violently and the seas to wash away their people and homes...[T]he ancient quake and tsunami devastated the western shores of Vancouver Island and the eastern coast of Japan.An estimate of how many generations had passed since the event[3] — which can be traced back to a date range in the late 1600s or early 1700s,[4] or which concur with the event's timing in other ways help pinpoint the timing.

The Huu-ay-aht legend of a large earthquake and ocean wave devastating their settlements at Pachena Bay, for instance, speaks of the event taking place on a winter evening shortly after the village's residents had gone to sleep.

It likely broke at least 1,000 kilometres of the boundary between the subducting Juan de Fuca Plate and the overriding North America Plate—a rupture about as long as California, or about Japan's length’s main island, Honshu.