Why Are the Bay of Fundy Tides the Highest in the World?

The Bay of Fundy (between New Brunswick and Nova Scotia, Canada) experiences the highest tidal range on Earth.

The Numbers

• Average range: 17 m (56 ft).
• Spring tide maximum: 21.6 m (71 ft) – recorded at Burntcoat Head, Minas Basin (Guinness World Record).
• Comparison: Global average ~1 m; most coasts 1–3 m. Fundy is 10–20× typical.

Why So Extreme? Resonance + Geometry

1. Natural period matching: The bay's length (~270 km) and depth create a natural seiche period of ~12.4 hours—almost exactly the M₂ lunar semidiurnal tide period (12h 25m). The basin resonates with the astronomical forcing.
2. Funneling geometry: The bay narrows and shallows dramatically toward the head (Minas Basin → Chignecto Bay). Conservation of energy forces the tidal wave to increase in height as width/depth decrease.
3. Correction: Not just "strong currents push water up." It's a standing wave resonance amplified by convergent geometry.

Ecological & Economic Effects

• Mudflats: Vast intertidal zones exposed twice daily → critical stopover for millions of shorebirds (semipalmated sandpipers, etc.) feeding on Corophium amphipods.
• Mixing: Extreme turbulence oxygenates water, drives nutrient cycling → high productivity (fish, lobster, scallops).
• Tidal power: Annapolis Royal Generating Station (20 MW, 1984–2019); new in-stream turbine projects (FORCE test site).
• Tourism: Tidal bore rafting (Shubenacadie River), Hopewell Rocks ("Flowerpot Rocks") walking on ocean floor at low tide.
• Navigation: Ports (Saint John, NB) require precise timing; reversing falls phenomenon.

Climate Change Note

Sea-level rise may alter resonance, potentially increasing range further—but also submerging marshes. Monitoring ongoing.