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 Earth’s watery blanket. At most places along the ocean shores, high tides occur regularly 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 natural 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 toward 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. For information on tide times on the Shubenacadie see our Schedule of Tides. The greatest difference between high and low tide ever recorded was at Burntcoat Head, Nova Scotia, in the Bay of Fundy’s Minas Basin.

On 8 February 1997, at Burntcoat Head, between the high tide at 2:07 pm and the low at 8:29 pm, the tidal range was 16.65 metres (54 feet 7 inches)!

Around 5 pm the tide was falling at the rate of one foot every four minutes. Earlier that day, around 11 am, the tide was rising at the rate of a foot every four minutes. This extreme tidal range occurred because the Moon was about as close to the Earth as it ever gets – the Moon was at perigee at 5 pm on 7 February with a Moon to Earth distance of 356,847 km, the shortest distance of any perigee during 1997. At the same time, the Earth to Sun distance was close to a minimum, with the Earth having passed perihelion on 1 January. Similar tidal ranges occurred in 1998, on 28 February, 1 March, and 30 March.