Fact #162
Earth & tides
Tides in the Bay of Fundy reach over sixteen metres, not because the Moon pulls harder there but because the bay takes about the right amount of time to slosh.
Water rocking end to end in that basin has a natural period close to the 12 hours 25 minutes between high tides, so each pull arrives in step with the last, like pushing a swing. Any bay with the wrong dimensions gets an ordinary tide; this one resonates, and moves a hundred billion tonnes of water twice a day.
Source: Fisheries and Oceans Canada; Garrett, Nature 238, 441 (1972) · checked Sep 2026