Why Are the Bay of Fundy’s Tides so High?

The Bay of Fundy is a marvel to behold. From its historic shipbuilding villages and Acadian forests to its rugged sea cliffs and serene marshland, it offers countless idyllic maritime landscapes for travelers to enjoy. Of course, what it’s best known for is a bit more...oceanographic. With a tidal range of some 47 vertical feet, the Bay of Fundy boasts the Guinness-certified highest tides in the world (eat your heart out, Bay of Khambhat). Visitors come from around the world to watch its enormous mudflats and towering rock formations transform into billowing waves and tiny islands over the course of 12 hours. It’s awe-inspiring to see boats go from bobbing in deep water to sitting on dry land—and it happens every day.

But though the result of this epic ebb and flow is obvious, its cause is a bit harder to understand. The key concept is an idea called tidal resonance—in essence the, err, notion that the motion of waves in a bay or cove can be reinforced by the motion of the tides. Like an adult pushing a child in a swing, the tide is perfectly timed to push waves farther into shore at high tide. As a result, when the tide goes out, it has considerably farther to go. By pure chance, the size and shape of the Bay of Fundy creates waves that move at the perfect speed to be pushed along by the tide.

These unique conditions create several other interesting effects as well. On the Saint John River, in the town of Saint John, you may view Reversing Falls, an area of rapids where the river narrows as it flows through a gorge.  This white water is unique because it switches directions every twelve hours—flowing violently upstream when the tide goes out.

In other regions, it’s possible to witness the strange phenomenon of a “tidal bore,” where a wave front of water flows upstream on top of a river flowing the other way. These bores are possible to surf or raft on in some areas. They can be viewed in the Bay of Fundy region on the Salmon, Petitcodiac, and St. Croix rivers.

Also of interest is the Old Sow whirlpool, the largest tidal whirlpool in the Western Hemisphere (and one of the five largest in the world). Caused by the confluence of turbulent currents where the Bay of Fundy meets Passamaquoddy Bay, it’s over 250 feet in diameter.

All of that said, the Bay of Fundy has considerable allure beyond its status as a scientific anomaly. Minke and finback whales ply its open water, as well as playful porpoises and harbor seals. The beautifully preserved Campobello Island reveals a hidden chapter in history with the cottage of Franklin D. Roosevelt—kept just as it looked in the 1920’s. Seaside walks provide ample opportunities to spot an ecstasy of seabirds—shearwaters, petrels, sandpipers, and even puffins—as well as bald eagles on the hunt. A warm Acadian culture offers vibrant maritime traditions—a delicious lobster-feast of cuisine, culture, and welcoming faces.