More settled science: Polar bears can only swim up to 100 miles, and they can also swim 426 miles

2011: More polar bear cubs die as Arctic ice melts | Reuters

There were 50 long-distance swims over those six years, involving 20 polar bears, ranging in distance up to 426 miles

2005: Polar bears drown as ice shelf melts - Times Online

“We know short swims up to 15 miles are no problem, and we know that one or two may have swum up to 100 miles. But that is the extent of their ability, and if they are trying to make such a long swim and they encounter rough seas they could get into trouble,” said Steven Amstrup, a research wildlife biologist with the USGS.