Bay of Fundy

Provinces: New Brunswick/Nova Scotia

Measuring up to 80km (50mi) wide at its mouth, the Bay of Fundy is a delta-shaped bay in the Atlantic Ocean, almost 300km (190mi) deep and penetrating the North American mainland between the Canadian provinces of New Brunswick and Nova Scotia.

The Bay of Fundy is neither the largest nor the deepest in the world, but its maximum tidal flow between low and high of 19m (10 fathoms) in the extreme north of the bay at Moncton and Truro is not exceeded anywhere else. Its average tidal flow is about 9m (30ft), but during the spring tides 13m (43ft) can easily be exceeded. Ebb and flow, brought about by the gravitational pull of the sun and the moon, occur when waves in the ocean are stationary. As a result of the earth's rotation, or coriolis power, and the shape of the oceanic basin the tidal waves revolve around a central point, or amphidrom. The determinant amphidrom in the North Atlantic revolves anti-clockwise once every 13 hours, producing a complete tidal change. The extended delta-like shape of the Bay of Fundy has an intensifying effect on the tides which are a mere 80cm (32in) high out in the open sea. The relative rise in the sea-level about 6000 years ago resulted in Fundy Bay being joined to the Atlantic, and from then onwards the tides were high. Since then the average tidal flow has continually increased, so that now during the spring tides it reaches up to 16m (53ft) in the furthermost corner of Fundy Bay. If in the future either man - by, for example, building giant tidal power-stations - or Mother Nature herself brings about marked changes in the shape of the bay that will almost certainly put an end to this fascinating natural spectacle.