This article records tradition as it has been passed down and reported. Its sources are not yet part of the atlas's verified catalogue.
Most coastlines in the world see a tidal range, the vertical difference between high and low tide, of no more than a few feet. The Bay of Fundy, between the Canadian provinces of Nova Scotia and New Brunswick, regularly exceeds fifty feet, the largest tidal range recorded anywhere on Earth. The gravitational pull driving that tide is the same pull acting on every other coastline in the world; the Bay of Fundy's extremity comes entirely from the shape of the bay itself.
The bay is long, narrows and shallows toward its inner end, funneling an enormous volume of water into a progressively tighter space as the tide advances, the same effect that speeds a river through a narrow gorge. More importantly, the bay's own natural resonant period, the time it takes a wave to slosh from the bay's mouth to its inner end and back, happens to be close to the roughly twelve and a half hour period of the tide itself. When a system's natural resonance closely matches the period of the force driving it, the response amplifies dramatically, the same physical principle that lets a properly timed push send a playground swing far higher than an equally strong push at the wrong moment. The Bay of Fundy is, in effect, a giant water container tuned almost exactly to the tide's own rhythm, and that near-perfect tuning, not unusually strong gravity, is what produces its extraordinary range.
The consequences are visible and economically significant. At the head of the bay, the incoming tide can reverse the flow of rivers, producing a tidal bore that runs upstream against the current, a phenomenon visitors travel specifically to watch on the Shubenacadie River. The same enormous volume of moving water has long made the bay a target for tidal power generation, from the Annapolis Royal tidal station built in the twentieth century to more recent in-stream turbine projects, though the extreme currents and ice conditions that make the bay attractive for power generation have also made sustained tidal power extraction there a genuinely difficult engineering problem, one still being actively worked out.