How High Can Bay Tides Go? Up to 53 Feet in the Bay of Fundy
Bay tides aren't uniform—they're **amplified by geometry**. The world champion:
Bay of Fundy (Canada) — Extreme Tidal Range
- Max recorded: **16.3 m (53.5 ft)** at Burntcoat Head, Minas Basin
- Mean spring range: 12–14 m (39–46 ft)
- Mechanism: Funnel shape + resonant period (~12.4 hr) ≈ M₂ lunar tide → **constructive interference**
- Volume moved: 160 billion tonnes per tide — equals all world's rivers combined
Why Most Bays Are Modest
| Bay Type | Typical Range | Reason |
|---|
| Wide, shallow (Gulf of Mexico, Hudson Bay) | 0.3–1 m | No resonance; energy dissipates |
| Narrow, deep fjords (Norway, BC, NZ) | 1–3 m | Constrained but not resonant |
| Estuaries with river flow | 1–4 m | Fluvial damping |
| Resonant funnels (Fundy, Ungava, Bristol Channel, Mont-Saint-Michel) | 8–16 m | Quarter-wave resonance |
Drivers of Daily Variation
- Spring vs. neap: Syzygy (sun-moon alignment) → 2× range
- Wind setup: Onshore wind piles water (+0.5–2 m); offshore subtracts
- Atmospheric pressure: 1 mbar ≈ 1 cm (inverse barometer)
- Storm surge: Cyclones add 1–5+ m on astronomical tide
Practical Implications
- **Navigation:** Tidal windows critical for deep-draft ports (Saint John, NB)
- **Energy:** Tidal stream turbines (FORCE test site, Minas Passage)
- **Ecology:** Intertidal zone = massive feeding ground (shorebirds, fish)
- **Recreation:** Tidal bore rafting (Shubenacadie, Petitcodiac)
Fundy proves: **shape writes the tide**. Every other bay is just a footnote.
Wanderlust World