Going beyond the end of the road in Ontario

It's a late August day in northeastern Ontario, and I've come to the end of the road. Beyond the end of the road, really. I'm on Moose Factory Island, a speck of land in the middle of the Moose River, near the mouth of James Bay. You can't get to this region, where most of the residents are members of the Cree First Nation, by car or bus.