Last Update
01-Nov-2009

   A tidal bore is a natural phenomenon which is seen in very few parts of the world. The Bay of Fundy is particularly noted for its extremely high tides, the highest in the world, and for its tidal bores.

   As is generally known, the rise and fall of ocean tides is caused by the gravitational "pull" of the moon on the earth's watery blanket. At most places along the ocean shores, high tides occur regulary every 12 hours, 25 minutes.

   In the open ocean the tide only rises and falls a fraction of a meter. However, in most V-shaped bays and inlets the tide enters the broad end and the water literally "piles up" as it moves up the bay. In certain areas, such as the Bay of Fundy, the natrual period of oscillation is very close to the tidal period and, just like water sloshing back and forth in a bowl, the rise and fall of the tide is greatly amplified.

   Thus, the tide water enters the bay at its widest point, and as it passes along towards the head of the bay, it is in effect squeezed by the ever-narrowing sides and by the constant "shallowing" of the bottom.

   At the very head of the bay this advancing tide becomes a wave varying from just a ripple to several feet in height, and this wave continues into and up the rivers which empty into the bay. This wave is referred to as a "Tidal Bore". Thus we have the phenomenon of a river changing its flow before your very eyes, created by the tidal wave, or bore, flowing in OVER the outgoing river water.

   The height of the tidal bore increases with the range of the tide. The range of the tide varies with the phases of the moon, the distance to the moon and other factors and can be obtained from the Canadian Tide and Current Tables published by the Department of Fisheries and Oceans.