THE PHENOMENON OF THE REVERSING FALLS
IN SAINT JOHN, NB, CANADA

The phenomenon of the Reversing Falls is caused by the tremendous rise and fall of the tides of the Bay of Fundy, which are the highest in the world. The natural southward-facing opening of the Bay of Fundy receives the on-rushing ocean tides directly, like a funnel. The tide-water is normal when it enters the bay at its widest point, but further up the bay it travels, the more it changes. It is, in effect, squeezed by the ever-narrowing sides and the constant shallowing of the bottom forcing the water higher up the shores. The low tide running out of the bay collides with the new, in-coming high tide, combining forces to make a higher wave coming in. The combination of wave forces is called resonance.

The Bay of Fundy tides are affected by the distance of the moon from Earth at this longitude. Here, in Saint John, the bay tides rise 28½ feet. When the tide is low, the St. John River, 450 miles long, empties into the bay. Between Fallsview Park and the Pulp Mill, the full flow of the river thunders through a narrow gorge. An underwater ledge 36 feet below the surface causes the water in the river to tumble downward into a 175-200 foot deep pool. Below the mill and under the bridge, the water boils in a series of rapids and whirlpools.

As the tides begin to rise, they slow the course of the river and finally stop the river flow completely. This short period of complete calm is called slack tide. It is only at this time that boats are able to navigate the Falls (except for the REVERSING FALLS JET BOATS which can ride at any time). Shortly after this slack tide the bay tides become higher than the river level and slowly the river begins to flow upstream. As the tides continue to rise, the reverse flow gradually increases and the rapids begin to form, reaching their peak at high tide. At this point the tidal waters are actually 14½ feet higher than the river. The effect of this reversal is felt upstream as far as Fredericton, more than 80 miles inland.

After high tide the bay tides begin to fall and the upstream flow of the river gradually lowers until the bay tides fall to the level of the river - once again resulting in another slack tide. The river then resumes its normal course and begins to flow back into the bay. The bay tides continue to fall below the level of the river until at low tide the rapids are again at their peak, flowing down stream. At this point the tidal waters are 14½ feet lower than the river level.

The tide rises and falls once about every 12 ½ hours. To best appreciate the Reversing Falls, you should try to view them at least twice on a given day – near low tide and near high tide.  There are three good ways to observe the Reversing Falls, all located in the Fallsview Park, not far from the Reversing Falls Information Centre. First, you can observe the phenomenon from the Falls View Park Banks which give you a direct view of the falls or, you can ride them onboard the REVERSING FALLS JET BOAT RIDES, for a thrilling cavalcade right in the centre of the Falls, or tour them onboard the REVERSING FALLS JET BOAT TOURS for a sightseeing tour alongside the Falls and in the harbour. The REVERSING FALLS JET BOATS are the only boats authorised to navigate in the Falls.

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