As of today, peak season now, through ~December 31. Earth Exhibit tracks the live conditions and flags it the moment it is on.
The Swellies are a complex tidal race in the Menai Strait where constricted channel geometry, submerged rocks, and large Irish Sea tidal ranges create strong currents, boils, standing waves and whirlpools.
The most dramatic flows occur on spring tides around new and full moons and during perigean spring events, making this a predictable but potentially hazardous marine spectacle.
Where to see it
A taste of where to see it. The full map, exact coordinates and the best timing for each spot live in the app.
| Viewing spots |
|---|
| Menai Bridge South Bank Viewpoint |
| Beaumaris Waterfront and Pier |
| + 1 more spot, with exact coordinates and timing, in the app → |
This is the short version
This page shows a taste. The app has the full list of where to see this, the exact timing, and live conditions for 1,000+ natural phenomena worldwide, so you know the moment one is genuinely worth the trip.