At least one sneaker containing a human foot washes ashore in the Pacific Northwest every year, and while this sounds like the premise of a murder mystery it's actually a fairly normal occurrence and not the result of foul play.
In December, 2017 human Mike Jonz and his dog Taz discovered a left foot wearing a white sock inside a black sneaker with a Velcro closure on a beach in British Columbia, the tibia and fibula still attached. So more of a leg than just a foot but a creepy find nonetheless, the kind which is so common on these coastlines there's a Salish Sea Human Foot Discoveries Wikipedia page.
So where are all these feet coming from:
“The BC [British Columbia] Coroners Service has been able to identify eight of the previous 12 feet, belonging to six individuals,” the agency said in a statement. “In none of the cases was any foul play involved.”
For starters, there are simply a lot of corpses in these waters. Kathy Taylor, a forensic anthropologist at the King County Medical Examiner’s Office, which has jurisdiction along the Seattle-Tacoma coast of Puget Sound, explained that this is a consequence of having a densely populated area on the coast.
Suicides and drownings are somewhat regular events around any body of water, and sometimes people who die of natural causes on the shoreline also get swept into the ocean.
Why do they wash up so often in this particular area?:
As for why body parts so often end up on the shore in the Salish Sea and not around other metro areas bordering water, like the San Francisco Bay Area or New York City, Parker MacCready, an oceanography professor at the University of Washington, said the story is simple. “Things that float at the ocean surface move with the currents, but also are pushed a bit by the wind, and this can be significant in getting them to shore,” he wrote in an email. “The prevailing winds here [around the Salish Sea] are west to east, and so floating stuff in this part of the Pacific gets blown to the coast effectively.”