Eleven kilometers of tunnel have been mapped beneath a large Ontario river. In places the passages stretch out across the bedding planes to nearly 90 feet in width. Some passages are still and cold, others have massive currents that threaten to sweep the unprepared off into blackness – one cave diver already lost his life there. The photo above shows an inland pool where one such tunnel breaks open close to the surface. Locals say that these places are great for fishing.