The biggest tides in the world: where and why

Where the biggest tides in the world are

Top spot goes to Canada’s Bay of Fundy. At the head of the bay, in Nova Scotia’s Minas Basin, the water can rise and fall about 53 feet (16 meters) between low and high tide. Ungava Bay, in northern Quebec, comes very close. After them, a handful of places reach or pass 30 feet: the Gulf of Saint-Malo in France, the Severn Estuary in Britain, Argentine Patagonia, Alaska’s Cook Inlet, Russia’s Sea of Okhotsk, northwest Australia and the west coast of Korea.

For a sense of scale: NOAA notes that islands in the middle of the ocean usually get tides of 3 feet (1 meter) or less. Here are the record holders, with the source for each figure:

Place	Country	Range between high and low tide	Source
Bay of Fundy (Burntcoat Head, Minas Basin)	Canada	53.4 ft (16.27 m) record; about 43 ft (13 m) on average spring tides	Fisheries and Oceans Canada and SHOM
Ungava Bay (Leaf Basin)	Canada	up to about 56 ft (17 m) on the biggest tides	Canadian Hydrographic Service
Gulf of Saint-Malo (Mont-Saint-Michel, Granville)	France	over 39 ft (12 m) on average spring tides; about 46 ft (14 m) at most	SHOM and Canadian Hydrographic Service
Severn Estuary (Bristol Channel)	United Kingdom	39 to 46 ft (12 to 14 m)	Natural Resources Wales
Río Gallegos estuary	Argentina	25.7 ft (7.8 m) average; up to 40.8 ft (12.4 m)	Argentine Naval Hydrographic Service
Turnagain Arm and Anchorage (Cook Inlet)	United States	about 39 ft (12 m) in Turnagain Arm; 29 ft (8.9 m) daily average at Anchorage	Canadian Hydrographic Service and NOAA
Penzhin Gulf (Sea of Okhotsk)	Russia	about 36 ft (11 m)	SHOM
King Sound (Derby)	Australia	37.5 ft (11.4 m) between the extremes predicted for 2018	Bureau of Meteorology
Incheon	South Korea	about 32 ft (9.8 m) on spring tides	Korean hydrographic constants (KHOA)

These numbers aren’t perfectly comparable. Some are averages of spring tides, others are the maximum measured or predicted, and some stations have far more years of records than others. That’s why Fundy and Ungava, or France and the Severn, are often described as tied. What doesn’t change is the big picture: only two bays on Earth top 50 feet, and both are in Canada.

Canada’s Bay of Fundy and Ungava Bay: over 50 feet

The Bay of Fundy lies between Nova Scotia and New Brunswick, just across the border from Maine. It narrows and gets shallower toward its head, where it splits into Chignecto Bay and the Minas Basin. At Burntcoat Head, in the Minas Basin, Fisheries and Oceans Canada reports the highest tide on record: 16.27 meters (53.4 feet). On an average spring tide, the range there is about 13 meters (43 feet).

That moves a staggering amount of water. Twice a day, about 3 billion cubic meters (nearly 800 billion gallons) flow into and out of the Minas Basin, and low tide uncovers some 400 square kilometers (about 150 square miles) of mud and sandflats.

Ungava Bay, in Nunavik, northern Quebec, is far more remote, but its tides are nearly as big. The Canadian Hydrographic Service puts both bays at the top, with ranges of about 16 meters (53 feet), and says their extremes reach up to 17 meters (56 feet). In Ungava, the biggest tides come at Leaf Basin, near the village of Tasiujaq. The figures for each bay come from different measurements, so the comparison between the two is still open.

The biggest tides in the United States: Alaska and Maine

Cook Inlet and Turnagain Arm, Alaska

The biggest tides in the US are in Cook Inlet, the long arm of the sea that reaches Anchorage. NOAA’s tide station at Anchorage shows an average of about 29 feet (8.9 meters) between the higher high tide and the lower low tide each day. The biggest predicted tides there span almost 39 feet (11.8 meters). In Turnagain Arm, which branches off southeast of the city, the Canadian Hydrographic Service puts the range at about 12 meters (39 feet). You can follow it day by day on the Anchorage tide page.

Turnagain Arm is also where to see a tidal bore, a wave that runs up the arm at the leading edge of the incoming tide. According to NOAA, Turnagain Arm and Knik Arm are the only places in the US where bores happen regularly. In Turnagain Arm, a bore forms nearly every day: it starts at the mouth of the arm within an hour after low tide at Anchorage, ranges from half a foot to 6 feet high, travels at 10 to 15 mph and takes about 5½ hours to reach the end of the arm. The biggest ones come with large minus tides around the new and full moon.

Down East Maine

On the East Coast, the tide grows as you head northeast toward the Bay of Fundy. At Eastport, Maine, right on the Canadian border at the mouth of the bay, NOAA gives an average of about 19 feet (5.9 meters) between the higher high and the lower low tide each day, nearly twice Boston’s 10 feet. The biggest predicted tides at Eastport span about 26 feet (8 meters). Check the Eastport tide page to see today’s range.

At the other end of the scale, much of the Gulf of Mexico gets only a small tide. We explain why in why some seas have almost no tide.

Europe: Mont-Saint-Michel and the Severn

Europe’s biggest tides are on both sides of the English Channel.

In the Gulf of Saint-Malo, between Brittany and Normandy, the tide grows toward the bay of Mont-Saint-Michel. According to SHOM, France’s hydrographic office, the average spring tide range is about 4 meters (13 feet) at the head of the Bay of Biscay, 6 meters (20 feet) at Brest and more than 12 meters (39 feet) in the bay of Mont-Saint-Michel. On the year’s biggest tides, it approaches 14 meters (46 feet).

The bay is so flat that height turns into distance: at low tide the sea pulls back and leaves the abbey surrounded by sand, and at high tide it becomes an island again. In nearby Saint-Malo, the smallest tides of October 2026 move 9.4 feet and the biggest about 37 feet, almost four times as much.

Across the Channel, the Severn Estuary, between England and Wales, has one of the largest tides on Earth. According to Natural Resources Wales, the range there is 12 to 14 meters (39 to 46 feet), largely because the estuary’s funnel shape concentrates the tide as it moves up the Bristol Channel. The Severn also has a well-known tidal bore that, as NOAA notes, has carried surfers upstream for miles.

Patagonia, Australia, Russia and Korea

• Argentine Patagonia. The estuaries of Santa Cruz province have some of the largest tides in the Americas. On the Río Gallegos, the average range is 7.8 meters (25.7 feet) and the maximum reaches 12.4 meters (40.8 feet), according to Argentine Naval Hydrographic Service data published by the country’s National Water Institute.
• Northwest Australia. Derby, on King Sound, has the largest tidal range of Australia’s major ports. For 2018, Australia’s Bureau of Meteorology predicted tides from 0.36 meters at low tide to 11.78 meters at high tide, a span of more than 37 feet.
• Sea of Okhotsk. In the Penzhin Gulf, in Russia’s far northeast, the tide comes just once a day and still reaches about 11 meters (36 feet), according to SHOM. It’s the largest once-a-day tide in the world.
• Korea. At Incheon, the port of Seoul, the spring tides of late October 2026 span about 9.8 meters (32 feet), based on our predictions from the harmonic constants of KHOA, Korea’s hydrographic agency.

Why there: resonance, funnels and wide shelves

In the open ocean, the tide is small. What turns it into a giant is what happens when it reaches the coast. Usually three things add up. If you want the basics of why the moon and sun move the ocean at all, start with what causes tides.

A wide continental shelf

When the tide moves from water thousands of feet deep onto a broad, shallow shelf, it slows down and grows taller, much like a wave approaching a beach. NOAA notes that tides can be magnified where they hit wide continental margins. Australia’s Bureau of Meteorology explains the big tides of its northwest coast this way, and SHOM uses it to explain the jump from 20 feet at Brest to more than 39 in the bay of Mont-Saint-Michel.

A funnel-shaped bay

If a bay narrows and shallows toward its head, the same water has less and less room and piles up. Fundy, Ungava and the Severn are all V-shaped. NOAA calls the Bay of Fundy the classic example of how a funnel-shaped bay can dramatically increase the tide.

Resonance: pushing a swing at the right moment

The key ingredient is resonance. Every bay has its own natural rhythm: the time it takes water to slosh from the mouth to the head and back, like water rocking in a bathtub. According to the Canadian Hydrographic Service, in Fundy and Ungava that rocking takes about 13 hours, very close to the Atlantic tide, which arrives every 12 hours and 25 minutes. Each new tide pushes just as the water swings back, like a parent pushing a swing at the right moment, and the motion builds to over 50 feet. NOAA explains Cook Inlet’s tides the same way.

These giant tides are almost all the twice-a-day kind. How tide patterns differ around the world is the subject of our guide to types of tides.

How to see a giant tide safely

Watching one of these tides is unforgettable: boats sitting on the mud that float hours later near the top of the pier, islands joining the mainland and cutting off again. But giant tides have real hazards:

• The water comes back fast. With a 40-foot range over about six hours, the third and fourth hours of the rise bring 10 feet of water each. Our guide to the rule of twelfths shows the math.
• The mud can trap you. The silty flats of Fundy, Cook Inlet or Mont-Saint-Michel can grip your legs like quicksand. Don’t walk out onto them unless you know the ground or go with a local guide.
• Respect the bore. NOAA’s best advice for Turnagain Arm is not to be in the water or near the shore shortly after low tide, especially on extreme low tides.
• Pick the right day. The biggest tides of the month come a day or two after the new and full moon, and the biggest of the year often fall near the March and September equinoxes. We explain the cycle in spring and neap tides.
• Check the tide for your exact spot. Inside a big bay, high tide can come at very different times from one town to the next, so look up the nearest station and plan your visit around the time of low tide, with a set time to head back.